Dissertations / Theses on the topic 'Baja California (Mexico) – Poetry'

I studied the in-water anthropogenic impacts on sea turtles, origins of sea turtles on foraging and developmental areas, their migration routes, and described regionally appropriate conservation needs. Sea turtles inhabiting Baja California waters originate on distant beaches in Japan, Hawaii, and southern Mexico. Results from genetic analyses, flipper tagging and satellite telemetry indicate loggerhead turtles (Caretta caretta) feeding along Baja California's coast are born in Japan and make a transpacific developmental migration of more than 20,000 km, encompassing the entire North Pacific Ocean and that East Pacific green turtles (Chelonia mydas) originate on and return to rookeries in Michoacan, and the Islas Revillagigedo, Mexico. Hawksbill turtles (Eretmochelys imbricata), once the target of a lucrative fishery for their shell, are now extremely scarce and only juveniles were encountered. The region's importance to the biology of sea turtles, regionally and Pacific-wide, warrants urgent conservation action. While protected legally, sea turtles are subject to furtive hunting and incidental catch. Coastal development, pollution, and boat collision are secondary threats. Annual consumption of sea turtles in the region is estimated at between 7,800 and 30,000 animals. Sea turtles are eaten regularly in most coastal communities and turtles are considered an irreplaceable traditional food. The decline of sea turtles in these waters has cost us both ecologically and culturally. Sea turtle recovery in Baja California, as all conservation activities, will be a matter of cultural and social evolution. For recovery to occur, strong, community-based incentives and educational programs are needed. In the near term, increased enforcement efforts, monitoring of mortality, and establishment of sea turtle sanctuaries are among the solutions. Without expansion to include community-specific initiatives such efforts may be futile. A long-term, multi-faceted sea turtle "conservation mosaic" program has been launched, consisting of community-based research on life history and population biology, an international education and public outreach campaign, regional sea turtle conservation areas, a monitoring and stranding network, and several policy initiatives that will permanently protect sea turtles and their habitat.

The plants of San Quintín (Baja California, Mexico) were documented through intensive fieldwork and the collection of herbarium specimens to create a checklist of species. This region is home to a diverse flora with high levels of local endemism and many rare plants. The flora documented in this study was compared to historical records from the region and shows the impact of agriculture and urbanization on the plants, including several extirpated species. A study of the perennial vegetation using a 1 km grid provides species distribution data for 140 native species, which were assessed to highlight areas of significant species richness for native, rare, and endemic taxa. Several non-native plants were also mapped to provide baseline data. Areas of conservation priority for the flora of Greater San Quintín are discussed in light of these combined findings.

One of the major environmental concerns in the world is the loss of biological diversity due to anthropogenic activities. Of special concern is the conservation of endemic species that are particularly vulnerable to extinction. The Mearns's squirrel (Tamiasciurus mearnsi) is endemic to the Sierra de San Pedro Mártir, Baja California. Federally listed as threatened in Mexico and as endangered by the International Union for Conservation of Nature (IUCN), little is known about the ecology of this southernmost Tamiasciurus. Interestingly, Mearns's squirrels exhibit deviations from common behaviors observed in other congeners such as lack of leaf nests (dreys) and larderhoards (middens), suggesting potentially unique adaptations. Herein, I reviewed the diversity and conservation status of the arboreal squirrels of Mexico. Using radio-telemetry and satellite imagery, I examined if the lack of dreys and middens may be associated with differences observed in nesting behavior, home-range dynamics, and life-history and behavioral tactics between Mearns's squirrels and other arboreal squirrels.Mexico harbors 14 species of arboreal squirrels, of which four are endemic, with the states of Chiapas and San Luis Potosí possessing the greatest diversity. Unfortunately, high deforestation rates in Mexico, and a dearth of information on their ecology, pose serious threats to the persistence of this squirrel diversity. Mearns's squirrels apparently are obligate secondary cavity-nesters with specific nesting requirements and their population possibly limited by the low occurrence of tree cavities in their habitat. The species seems to have lost the territorial behavior that is characteristic of the genus Tamiasciurus. Home-range dynamics of Mearns's squirrels are similar to nonterritorial Sciurus squirrels. Although reproduction and survival are similar to other Tamiasciurus, the species is heavier and apparently larger while exhibiting important variations in their behavior compared to other congeners. The lack of dreys and middens appears to be associated with the unique tactics adopted by Mearns's squirrels to persist in the Sierra de San Pedro Mártir. The species provides an important opportunity to learn more about geographic variation in nesting behavior and the evolution of territoriality. Large trees and snags that facilitate cavity formation are critical for the conservation of this species.

The Maneadero Basin is identified as a transtensional sedimentary basin along the Agua Blanca Fault (ABF) in the southern limit to the "Big Bend" Domain of the North American-Pacific plate boundary zone. The ABF exhibits both the dextral and normal components of slip. This creates an interesting setting for the formation of the Maneadero Basin because structures with orientations similar to the ABF are typically contractional (e.g.: Puente Hills Fault, Whittier Fault, and Rancho Cucamonga Fault). The question if this basin is evidence of plate-scale transtension or local extension associated with bends/stopovers along the ABF is addressed by this study with three working hypotheses. The hypotheses presented by this study are: 1) the basins formed by a dip-slip component on the ABF and truly are an expression of regional transtension, 2) the basins formed at right steps along the dextral ABF, or 3) the basins formed as a result of juxtaposing basement blocks with disparate topographies. Each of these hypotheses would produce unique basin geometries and structures within and around the Maneadero Basin. To test these aforementioned hypotheses, a multi-disciplined study was conducted in the basin. A structural dataset was collected to identify kinematics and offsets of faults both within and bounding the basin. A gravity survey was also conducted to image the basin geometry. The results of the study show an asymmetrical gravity anomaly that closely follows the trace of the ABF. The amplitude of the anomaly is 54 mGal, the gradient of which is steepest around the ABF and shallows away from the fault to the north and east. Forward models of this anomaly indicate the ABF is a steeply north dipping fault. The gravity anomaly also indicates that the deepest part of the basin is located close to, but not coincident with the ABF and the basin gradually shallows to the northeast. This geometry is consistent with the hypothesis that the basin results from dip-slip on the ABF. This idea is also supported by the structural data, which includes fluvial terraces that have been uplifted and offset by faulting on the ABF, and by the presence of a normal fault on the ABF in the center of the basin. The third hypothesis is also supported by models of the gravity data, which suggest a deep (~900m) bowl shaped erosional feature in the bedrock. Dextral slip on the ABF juxtaposes the topographically high Punta Banda Ridge with this topographically low feature. Overall, the data presented in this study suggest the formation of the Maneadero Basin results from is a combination of the dip-slip component on the ABF and juxtaposition of the topographically elevated Punta Banda Ridge with a topographically lower basin of Bahia Todo Santos and Valle Maneadero. Geodetic data strongly suggest that the difference in motion of the Baja Microplate (south of the ABF) to the disrupted southern California Block (north of the ABF), and the orientation of the ABF relative to that motion, is causing transtension in the Maneadero Basin. This combined with strike-slip juxtaposition of different topographies allowed for the formation and evolution of the Maneadero Basin.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmosphere and Planetary Sciences, 1988.
Includes 1 folded map in pocket.
Includes bibliographical references.
by Joann Miriam Stock.
Ph.D.

As mass tourism is spreading throughout Latin America, haphazard growth is threatening the environment and local communities. In an effort to mitigate social and environmental impacts an alternative approach towards tourism development utilizes principles of ecotourism and smart growth to balance tourism, community, and environmental goals in order to maintain a healthy environment and contribute to the local community. Located several miles south of the town of Todos Santos in Baja California Sur, Mexico, Las Palmas is a 490 acre site with a mixed use development focused on ecological preservation and the integration of tourism with the local community. Entirely pedestrian oriented, the development includes a 46 unit ecolodge that is connected to a town center composed of a variety of housing types, and features commercial services, selected retail, and fitness and community centers. A 14 acre organic farm weaves through the development providing fresh vegetables to the local market and restaurants. 95% of the site is set aside as permanent natural open space run by research facilities that responsibly guide visitors through its natural beauties. Sustainable practices and research at Las Palmas include an onsite constructed wetland to treat and reuse wastewater, energy-efficient design strategies, a solar harvesting farm, an onsite agricultural center, and ecological regeneration.

Planners expect infrastructure development underway in Baja California to launch a wave of tourism. Managers will need information concerning the natural environment. This study focuses on the floral richness of the islands of Bahia de los Angeles, Baja California, Mexico. Results include island plant species inventories; a phytogeographic analysis evaluating the effects of island characteristics on plant species richness; a current human impact analysis, on floral richness; an evaluation of threats to floral richness and environmental health, including a non-native plant analysis; and management recommendations for preventing depletion of the native plant species richness on these islands from increased visitation. Floral richness ranges from 2 to 74 species per island. The best predictors of floral richness are the island area and the seabird presence or breeding. I recommend a combination of careful monitoring, dissemination of educational materials, and increased enforcement of current restrictions on island use to minimize human impacts.

The Mexican Ministry of Education (SEP) recognizes that teachers in general possess no training in environmental education or in strategies that facilitate participation amongst students. However, following the Mexican government approval of the Law of Environmental Education, in 2005, the inclusion of environment education in the elementary school curricula of Baja California Sur, Mexico, has become a priority. This study approaches this shortfall to consider the use of dialogic teaching as a strategy for increasing environmental awareness, whether if it can support children’s own sense of agency and whether it can successfully be incorporated into the permanent curriculum of Baja California Sur classrooms. The study takes a sociocultural approach drawing on the works of Vygotsky (1962, 1981), Barnes (1976, 2008) and more recently, Alexander (2008) and Mercer (2004, 2008). In particular, the study adapts the work of Mercer’s Thinking Together programme (2008) which was used to create a programme of work piloted in 7 schools, and as a theoretical foundation for the analysis of children’s’ recorded oral interchanges and written narratives. The research was conducted using a mixed methods approach to acquire and analyse qualitative and quantitative data. Its main focus is on the narratives produced by the children in the study as markers of improved environmental knowledge and awareness. The study also used reflexive researcher narratives following Clough (2002) and Denzin (2008) in which the researcher enters and acknowledges his own impact in the research environment, and explains this interaction to the reader through a narrative. The results were separated as quantitative and qualitative results. Quantitative data records significant gains in environmental knowledge indicators and in the count of dialogic and environmental keywords. Qualitative analysis records improvements in several aspects of the dialogue dynamics within the classroom, and in all the measured indicators.

Previous studies have suggested four hypotheses regarding the outcomes in the migration-fertility relation (i.e. 'socialization', 'adaptation', 'selectivity', and 'disruption' effects). However, there has been a lack of attention to the intervening mechanisms that help to understand the interaction between social factors and the reproductive patterns of migrants, and that has led to contradictory findings. In this thesis a Proximate Determinants approach is used as the appropriate analytical framework to elucidate the interaction between geographical mobility and reproductive behaviour, and its macro-demographic policy implications. This framework is used to analyze the reproductive behaviour of the migrant and native groups of Baja California, Mexico. The main data source used for this analysis is the 1986 Baja California Demographic Survey (BCDS), which was based on a probability self-weighted multi-stage household sample, selected from four independent Municipal sampling frames. In relation to those groups of the population of Baja California, the two main findings of this study are: i) patterns of marriage, contraceptive use and effectiveness, and the practise of breast-feeding amongst the native group seem to reflect a more 'modernized' attitude toward fertility behaviour, since in relation to the migrant group, lower proportions marry and they marry at older ages; higher proportions use contraception, and; fewer breast-feed and for shorter periods than their migrant counterparts, and; ii) regardless of birth-cohort, migrant women who spend their formative period in a rural environment, are more likely to achieve 'high' marital cumulative-fertility than native women in the same birth-cohort who spent their formative period in a urban setting and, furthermore, after controlling for education there is no evidence that within a given birth-cohort, migrants with longer periods of exposure are more likely to have 'low' marital cumulative-fertility than women of the same age who had shorter exposure periods to the new socio-economic environment.

Continental rifts are commonly flanked by zones of high elevation. Proposed uplift mechanisms include active and induced asthenospheric upwelling, and isostatically driven lithospheric flexure. Although these hypotheses make testable and distinct predictions of the relative timing of crustal extension and rift flank uplift, the difficulty of closely constraining these processes in modern or ancient rift zones means that the issue remains controversial. This study focuses on the Loreto rift segment of the Baja California peninsula, which forms the western margin of the Late Neogene Gulf of California rift. The Loreto region is characterised by a prominent east-facing rift escarpment which separates a low-elevation coastal plain, which hosts rift-bounding faults, from a west-tilted, topographically asymmetric rift flank, incised by west-draining canyons. On the coastal plain, slip on the rift-bounding Loreto fault has driven westward retreat of the escarpment. Footwall exhumation due to escarpment retreat is reconstructed using the apatite fission track and apatite (U-Th)/He low-temperature thermochronometers to constrain the minimum age of escarpment retreat and thus also Loreto fault slip. On the rift flank west of the escarpment, canyon incision depths are obtained by analysis of digital elevation models and used as a proxy for minimum uplift magnitude. The timing and rate of rift flank canyon incision, a proxy for the timing and magnitude of rift flank surface uplift, is constrained using 40Ar/39Ar dating of lavas which display cut and fill relations with the rift flank canyons. These lavas also provide a resistant cap atop canyon interfluve mesas, and the extent of this resistant cap likely controls the extent of rift flank catchment denudation in response to uplift. The principal finding of this thesis is that rift flank surface uplift was coeval with crustal extension at Loreto, consistent with predictions made by models of rift flank uplift driven by the flexurally-distributed isostatic response to the lithospheric unloading associated with crustal extension.

Migration, ethnicity and cultural pattern are reviewed. The research questions how accurately the prehistoric archaeologist can interpret migration and ethnicity by means of a review of the modern migration of a group of Russian sectarians to Baja California, Mexico. Excavations undertaken in seven households at different levels of assimilation with their Mexican and Indian neighbors suggests that material culture does reflect ethnicity under these best of all archaeological circumstances. A methodology for the determination of prehistoric migrations is suggested. It concludes that "cultural pattern" is a more useful concept than "ethnicity" in the determination of archaeological migrations.

This research explores the politics of development on the East Cape of Baja California Sur, Mexico. Based upon twelve months of ethnographic research and participant observation, primarily in the coastal community of Cabo Pulmo, the researcher investigates and documents how local residents respond to the social and political implications of impending mass tourism development in the region. Rising land values, real estate speculation, and intensifying conflicts over land ownership were some of the earliest symptoms of this process. The central argument is that social conflicts over development are often based in deeper, fundamental political struggles over land—and the ability to participate in the development process itself. This represents an important contribution to our understanding of the political and social dynamics of development, which, in the literature, are often framed in abstract terms of debate that remain highly detached from the lived realities of the people who stand to lose the most if development goes awry. Using the concepts of value, development, community, and sustainability as theoretical starting points, this research argues that conflicts over development should be seen as struggles for inclusion and participation above all else. Ultimately, the conclusion of this research is that conflicts over ownership of and access to land continue to impede alternative forms of development that seek to avoid the negative social, political, and economic consequences of traditional mass tourism models.

The Santa Rosalia basin is a NW-SE elongated and fault limited basin, which evolved from Upper Miocene to Pleistocene time. The transtensional Upper Miocene Santa Rosalia basin located in central Baja California, consists of almost 500 m of nonmarine to marine sedimentary rocks, with tuffaceous beds interbedded in its lower part. The sedimentary rocks consist of the Boleo Formation, which is 200 to 300 m thick and is dominated in its lower part by marine transgressive sediments and evaporite bodies followed by 170 to 300 m of clastic coarsening upward fan-delta marine-nonmarine sequence. The clastic sequence presents at least three well organized upward coarsing cycles (90-100 m thick each one). Each cycle represents a prograding fan-delta formed probably as a consequence of large and repeated vertical movements of the basin floor with respect to source areas, during the early stage of the opening of Gulf of California. Coeval with the deposition of the clastic sequence of the Boleo Formation there was extensive ash volcanism which originated from a volcanic center north of the basin. Copper-cobalt-zinc stratiform ore bodies (mantos) are hosted within the tuffaceous fine facies in the bottom of each sedimentary cycle. At least five mantos were recognized named as 4, 3, 3(1), 2 and 1. Ore minerals and their textures, the geometry of the mantos and elemental zonation, suggest a diagenetic origin for the different ore bodies. The lowest manto, 4, in the district seems to have a geological correspondence with the Lucifer manganese deposit north of the district associated with hot spring mineralization. Manto 3, 3(1), 2 and others all of which occur at a higher stratigraphic level than manto 4, are associated with mineralized fluids sourced from NW-SE faults. Fluids moving through the conduits crossed an oxidation-reduction boundary with the consequent precipitation of sulfide under reducing conditions. Sulfur and carbon-oxygen isotopes studies support anoxic conditions and a bacteriological origin for the sulfur and a mixture of seawater and freshwater during the formation of the mantos. Cu/Co, Cu/Zn and Co/Zn ratios and Cu-Co and Zn absolute values in the mantos support a horizontal and vertical zoning produced by low temperature up-ward moving solutions. The spatial and temporal correlation of the Boleo deposit with the opening of the Gulf of California indicate that the rifting setting might be the source of the metals and the same time might have induced the migration of the ore fluids.

The San Fernando Channel System is a superbly exposed submarine channel system of late Cretaceous age located on the Pacific coast of Baja California, Mexico.  High-resolution mapping and extensive system-wide correlation panels coupled with detailed sedimentology studies and interpretation of high-resolution photomosaics have shown that the system comprises a distinct hierarchy of stratigraphy components.  Extensive outcrops have allowed a detailed submarine channel model to be proposed which describes architecture and facies spanning outcrop to seismic scales. Channel complex sets are the largest mappable component within the system and are bounded by basal system-wide erosion surfaces.  Each set shows a consistent stratigraphic evolution comprising 3 distinct stages each characterised by distinct channel complexes. Channel complexes in Stage 1 are predominantly coarse-grained, highly amalgamated and confined within an extensive composite erosion surface. Stage 2 is dominated by channel complexes which are finer-grained, less amalgamated and laterally flanked by internal levee deposits. Stage 3 relates to the shutdown and gradual abandonment of the system and is dominated by fine-grained turbidites and well developed condensed intervals. The stratigraphic variation observed within the channel system is linked to sea-level fluctuations.  However, throughout the system, local contemporaneous faulting is shown to have a high degree of control on the location of sedimentation and commonly overrides the normal sea-level influenced depositional evolution.  Local faulting is also shown to profoundly affect both the local channel-fill type and the stacking patterns of architectural elements and channel complexes.  Stacking patterns of individual channel complexes are generally more predictable in Stage 2 than in Stage 1 which is attributed to the variation in relative confinement of the individual channel complexes.

Coves of Departure: Field Notes from the Sea of Cortez is a literary natural history presented in mixed forms of nature memoir, personal essay and redacted field notes. Intended as narrative nonfiction for general readership, it focusses on the natural history of Mexico’s Baja California peninsula, attending especially to the littoral zone of the Sea of Cortez. Numbered chapters narrate several sea kayak expeditions led by the author to the Isla Espiritu Santo archipelago of Baja California Sur. Chapters chronicling discrete expeditions are sectioned off by two long interludes that describe natural history explorations in the northern state, Baja California. The title essay, which transitions between the second interlude and the final chapter, investigates natural history from the perspective of material ecocriticism,.

La présente thèse introduit dans une perspective communicationnelle une étude qualitative analysant l'usage des Technologies de l'Information et de la Communication (TIC) dans des cours d'enseignement supérieur en ligne et mixtes. Le but de notre travail était d'étudier les cours à la fois en tant que produits médiatiques et en tant que pratiques sociales. Le document est divisé en deux parties : la première présente un résumé des approches théoriques et méthodologiques concernant l'utilisation des TIC, et décrit notre modèle d'analyse, comprenant deux dimensions (technologique et communicationnelle) situées à deux niveaux interconnectés. La deuxième partie décrit le contexte de notre recherche et l'application du modèle à une situation institutionnelle spécifique, celle de l'Université Autonome de la Basse Californie. Nous avons appliqué un questionnaire et réalisé des observations au cours d'un semestre afin d'identifier les caractéristiques des cours en ligne comme produits médiatiques. Le travail sur le terrain a également inclus des entretiens semi-structurés pour identifier les conditions de la production des cours par les professeurs. Les cours analysés sont présentés dans une typologie basée sur les intentions du concepteur. Les cours en tant que pratiques sociales ont été analysés depuis la perspective des étudiants et des professeurs
This thesis reports a qualitative study analyzing the use of Information and Communication Technologies (ICT) in online and blended higher education courses from a communicational perspective. The purpose of our work was to study the courses both, as final media products and as social events. The text is divided into two sections : the first part presents a summary of the theoretical and methodological approaches on the use of ICT, and describes our model of analysis, which contemplates two dimensions (technological and communicational) in two interrelated levels. The second part describes the context of our research and the application of the model within a specific institutional environment che mra: the Autonomous University of Baja California. In order to identify the characteristics of online courses as media products, we conducted field work during one semester, consisting of the application of a questionnaire and observations regarding the online courses, as well as semi-structured interviews to identify the conditions of the teachers’ production of the courses. We present a typology of the analyzed courses according to the teachers' intentions; we observed that the teachers' teaching style and pedagogical intentions have a greater influence on the way they use the ICT during online courses, regardless of their technological skills. The courses as social practices were analyzed from the perspective of both, students and teachers

This thesis investigates a sequence of 17 cycles of coarse-grained syn-rift delta progradation in the Loreto basin, Baja California Sur. The Loreto basin is a Pliocene half-graben bounded by the 30 km long easterly dipping extensional Loreto fault, with 1.5 km throw. The Loreto basin uniquely provides a temporally constrained setting that couples preserved alluvial architecture with marine depositional geometries that enables these controls to be distinguished. The depositional architecture of each cycle is reconstructed by correlating 61 close-spaced (20 m to 320 m), detailed (1:5000) sections. Of the 17 progradational cycles, the lower 11 are particularly well exposed. Temporal constraints achieved through the dating of two sequence bounding tuff horizons, give an average duration for a single cycle of delta progradation to be 14±8.6 kyr., with most cycles being <10 kyr. This duration is too short to be explained by Pliocene eustatic variations (41 kyr). A consistency in measured palaeocurrents towards the NNE suggests that lobe switching was not a significant factor in controlling delta architecture. A facies framework is established that recognises both shoal-water and Gilbert-type delta deposition in the basin. The facies framework, coupled with reconstructed depositional architectures reveals that 7 of the 11 lower cycles, and at least one upper cycle (12) exhibit a palaeoseaward transition from shoal-water to Gilbert-type deltas. This nucleation of clinoforms with initially oblique, but increasingly sigmoidal geometries is characterised by a down-transport development of forests, which increase in height from 4 m to >26 m as they are traced basinward. Each cycle is capped by a shell bed that records drowning of the delta top. The geometry, and specifically the nucleation of clinoforms in single cycles of progradation requires a continued basinward increase in bathymetry. In one case this increase can be attributed to the topography of an underlying delta cycle. However for most of the cycles the increase in bathymetry can only be achieved if the rate of tectonically-controlled accommodation creation accelerates during their deposition.

One dilemma in sedimentology is that multiple depositional processes can produce similar features while one formative process can generate multiple patterns. A comparison of (1) depositional energy trends from grain size and primary structures, (2) placement within a stratigraphic hierarchy, (3) ichnofacies type, diversity and distribution, and (4) sedimentary body type and associated architectural changes are used to assess the causal mechanism. Variations of these attributes reflect flow initiation processes (flood vs. failure), depositional processes (flow stripping, overspilling or bottom current reworking), and preservation (thin-beds bounded by erosional channels). Cretaceous and Tertiary outcrops in the Mesa San Carlos area expose four different thin-bedded sandstone types (TBS). This document presents a matrix of the most important attributes used to recognize them: (1) hyperpycnite successions (4-15m thick) are interbedded with slope mudstone deposits that together form tabular (85m thick; >1km wide) successions, with sandstone channels and scours common at the base and mass transport deposits present at the top, (2) Wedge-shaped TBS turbidites that flank and confine multistory channelbelts up to 90m thick that thin and pinch out within 500m of interdigitated but stacked conglomerate channels, (3) TBS turbidites separating channel bodies form 25m-thick and 230m-wide preserved remnants, and (4) TBS contourites comprising <3m wide sandstone lenses amalgamated laterally to form tabular bedsets. Paleocurrent indicators change from unidirectional offshore during hyperpycnal flow to slope parallel flow during waning energy conditions of this mudstone-rich cycle. The matrix allows for a sedimentological hierarchy that describes the spatial and temporal organization of hydrodynamic facies that link together to form sedimentation units recording changes in the longitudinal structure of the flow. Other results include the field- and lab-based mudstone analysis that allows recognition between hemipelagic and pelagic mudstones; the revision of the regional stratigraphy for the El Rosario Formation, and an energy matrix for hyperpycnite channels and scour deposits recording the downstream and vertical changes in sedimentary bodies, grain size and primary structures.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996.
Includes bibliographical references (p. 126-139).
by Richard A. Bennett.
Ph.D.

Submarine channel-levee systems are spectacular. geomorphological features extending down the continental slope and into the deep ocean basins. The evolution of channel-levee systems in relation to the flows which create them is particularly poorly understood, due to the inherent problems associated with direct monitoring. Additionally' previous lithofacies architecture models of submarine channel-levees, derived from seismic data, isolated core data and limited field studies currently have a limited resolution. Field observations of a submarine channel-levee complex within the Rosario Formation, Baja California, provide high resolution data of lithofacies and levee . depositional thickness decay along transects perpendicular to the channel axis. Within the levee, both sandstone thickness and the overall proportion of sandstone decrease away from the channel axis, in a channel-normal sense, according to a power-law.. Spatial variation in sedimentary structures away from the channel axis is also predictable and provides an important link to the depositional flow regime. The vertical succession within the levee indicates that the levee crest migrated outwards from the channel in response to increasing flow magnitudes and/or decreasing levee relief. Additionally, the spatial variation of ichnofacies within the levee is quantified and indicates a 'bioturbation front' which is indicative ofproximity to the channel. Intra-channel facies of the canyon confined portion of the· system include conglomerate scour fills and laterally amalgamated channel fills segregated vertically by overbank facies. Scours formed across previously 'quiet' areas, then coalesced into. what became the principal transport pathway. Scour fills can be traced laterally into thick sandstones which in tum pass laterally into a confined levee. Thin conglomerate bodies have a common facies association of matrix rich margins and a central wellsorted traction dominated deposit, these are interpreted as levees formed by frictionalfreezing at the margins of the flow. Axial parts of the channel fill are dominated by lateral accretion deposits indicating that these channels had a high degree of lateral mobility; this is also indicated by the rapid vertical alternation between thinly interbedded turbidites and thicker conglomerate packages. Laboratory modelling demonstrates that channel outer-bend sedimentation occurs from weakly confined flows, conversely more confined flows deposit at the inner bend; this may partly explain the spatio-temporal longevity of planform geometry commonly observed in submarine channels. The degree to which flows deposit overbank also relates to the degree of confinement, levee growth therefore reflects the degree of confinement. As levees increased in height their thickness along channel-normal profiles was increasingly well described by an exponential decay function. Additionally, sediment waves formed on the flanks of the levees, these commonly had intricate planform geometries which were found to relate to vortices which formed along channel margi~s due to the shear stress generated by faster moving and denser channelised flow. These vortices enlarge downstream and away from the channel as they decelerate across the overbank; in natural systems, vortex formation may explain the palaeocurrent swing which has been observed in both modem and ancient levee sandstones.

Thesis (Ph. D.)--University of California, San Diego, 2010.
Title from first page of PDF file (viewed March 30, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 384-401).

A descriptive case study approach and 34 indicators was used to examine the socio-economic impacts of whale watching tourism in the Laguna San Ignacio (LSI) World Heritage Site - located within the El Vizcaino Biosphere Reserve in Baja California Sur, Mexico. The framework measured both the socio-economic changes, and the economic viability of the local and regional operators. This approach led to a detailed understanding of the underlying, and often complex, inter-related factors that shaped the ecotourism development in LSI between 1994 and 2002. It identified strengths and weaknesses of current ecotourism development making it a valid tool for evaluating and improving these activities in any biosphere reserve. More specifically the objectives were to examine: 1. How existing ecotourism operations and their activities in the LSI have changed since 1994; 2. Whether these changes have made ecotourism a more viable socio-economic development alternative for the local communities; and 3. Which strategies may be useful in overcoming identified barriers to further socio-economic benefits both from existing and future ecotourism activities. The results strongly suggested that the benefits from ecotourism improved significantly between 1994 and 2002. Economically this was reflected in growth of visitor numbers (50%), employment (100%) and local and regional revenue approximately 70% (or 55% in real terms adjusting for inflation). Social benefits were seen in more cooperation among previous antagonistic stakeholders; a wider distribution of ecotourism benefits; some improvement in living standards and increasing local support for the Reserve. Politically, local stakeholders became more empowered through involvement in tourism related management activities. The viability of the local and regional operators also improved significantly as they became more sophisticated in their product offerings, enhanced their facilities and gained a market share of ecotourism relative to the foreign operators. These improvements were particular true for the operators that sold package tours. However, the analyses also revealed a number of barriers with the most important ones being: • Unresolved historic land use conflicts over rights to land with ecotourism possibilities; • Lack of activities diversification possibilities outside the tourism season; • Stagnating visitor numbers; • Uneven business skills among operators; • Poor marketing and promotional efforts; • Insufficient ecotourism infrastructure; • A proposed ecotourism tax; • Low profit margin of the ecotourism operators; and • Lack of funding for further investments To alleviate these threats and barriers 13 general strategies were identified. An elaboration of these resulted in 39 concrete operational strategies on how potentially to implement them.

Northwestern Mexico is characterized by different metallogenic provinces that are included along the Basin and Range, the Sierra Madre Occidental, and the Baja California geological provinces. With the purpose of contribute to the current understanding of the mineralizing processes, the present study focused on two important copper metallogenic provinces: the Cananea Porphyry District in Sonora, and the Sediment-hosted Stratiform Copper- and Mn-deposits in Baja California Sur. The U-Pb zircon ages from the mineralizing porphyries from Cananea district suggest a continued magmatic activity period of ~6 Ma. Also suggests a period of ~20 Ma for the entire magmatic activity in the district. The Re-Os molybdenite ages demonstrate five well-constrained mineralization events in the district; the main mineralization is constrained over a short period of time (~4 Ma). The new molybdenite age from the Pilar deposit documents the oldest mineralizing pulse, suggesting possibly the initiation of the Laramide mineralization in northern Sonora. A detailed study of Mariquita porphyry Cu and Lucy Cu-Mo deposits in the Cananea district was performed. Four hydrothermal stages were defined in Mariquita, whereas a single hydrothermal pulse characterizes Lucy. Emplacement depths between 1-1.2 km, and temperatures between 430-380ºC characterized the mineralization from Mariquita, whereas deeper emplacement depths and higher mineralization temperatures characterized Lucy. The stable isotope systematic and fluid inclusion data determined that the mineralizing fluids in Mariquita deposit are essentially magmatic during the earlier hydrothermal stages, whereas the last stage is the mixing between magmatic and winter meteoric-waters. The mineralizing fluids from Lucy deposit are magmatic in origin. A comprehensive study was performed in the Cu-Co-Zn-Mn ineralization of the Boléo District, and Mn-oxide mineralization along the eastern coast Baja California Sur. The REE and trace element in the Mn-oxides demonstrated the exhalative nature of the mineralizing hydrothermal fluids, and exclude the hydrogenous nature. The stable isotope systematic in ore and gangue minerals, along with the Cu-isotope data helped to decipher the nature of mineralizing and non-mineralizing fluids. The application of Pb, Sr and Re-Os isotope systems was applied to constrain the nature of the fluids involved during the mineralization processes and that the metal sources.

En el planteamiento previo de este trabajo nos propusimos cinco objetivos que hemos desarrollado a lo largo del estudio y que se detallan a continuación. 1) Documentación del mural La documentación gráfica del mural ha consistido en la realización de un calco digital del mural en base al programa Photoshop y con la ayuda de la aplicación DStrech. A partir de la documentación gráfica hemos identificado 194 motivos en distintas categorías de figuras animales, humanas y elementos esquemáticos y abstractos distribuidos en cinco sectores de la cueva. Todos estos motivos están reproducidos a escala en el calco general y situados en la planimetría de la cavidad. Además, hemos elaborado una aplicación de base de datos específica para nuestras investigaciones referentes al arte rupestre de las sierras centrales de Baja California. La intención es tener unas descripciones estandarizadas que permitan comparar los datos formales de las figuras de una cavidad entre sí y respecto a otros murales. En este estudio incluimos la descripción de la base de datos y su funcionamiento, así como la información perteneciente a la cavidad de El Ratón en forma de ficha individual de cada figura. 2) Proceso de realización del mural La documentación del mural ha servido para establecer el orden de superposición de las figuras que están en contacto y muestran una estratigrafía cromática. El establecimiento de estas superposiciones no está exento de problemas, derivados principalmente de la apreciación del anclaje de los pigmentos, las transparencias de los colores, los repintes y las reelaboraciones de las figuras. A partir de esta información hemos establecido el proceso de ejecución del mural. Para ello hemos tenido también en consideración elementos compositivos y rasgos formales de las figuras pintadas. El resultado son siete fases consecutivas dentro del proceso muralista. Hemos detallado los puntos en la documentación en los que nos hemos basado para establecer el proceso para que pueda juzgarse su idoneidad, y proponemos estudios más detallados que incluyan la elaboración de láminas delgadas en algunos puntos del mural para cerciorarnos de las superposiciones. Por otra parte, hemos confrontado la propuesta de fases que hemos establecido en El Ratón con las fases que R. Viñas propuso para La Pintada y hemos podido apreciar que algunas formas que caracterizan fases consecutivas de La Pintada siguen el mismo patrón en El Ratón. Esto es especialmente apreciable en la evolución del perfil de los cuerpos y la posición de las patas de los cuadúpedos. 3) Contexto cronocultural Durante mucho tiempo los Grandes Murales se han considerado como un fenómeno relativamente homogéneo vinculado con la cultura Comondú, en un periodo de tiempo incluido en las últimas fases de la prehistoria bajacaliforniana. A partir de las observaciones en distintos murales, nuestro equipo de trabajo advirtió que las fases pictográficas que se observan en algunos frisos podían contravenir esta idea inicial y descubrir que el proceso pictográfico de las sierras centrales de Baja California es dilatado en el tiempo. La documentación realizada por R. Viñas en La Pintada y ahora la que presentamos para el caso de El Ratón confirman esta hipótesis: hay una diversidad de momentos pictóricos en los murales que evidencian cambios culturales en un proceso diacrónico dilatado. R. Viñas propone una distinción entre los Grandes Murales con distintas fases internas —en La Pintada propone cuatro fases para los Grandes Murales—; otra etapa pictórica con la inclusión de nuevas formas gráficas que mantendrían elementos de los Grandes Murales, a la que llama «Tradición Gran Mural», y una etapa final en la que predominan los elementos esquemáticos y abstractos y que se desvincula formalmente de los Grandes Murales. Este esquema coincide con nuestras observaciones en El Ratón, donde las fases 1-3 corresponden plenamente a los Grandes Murales, las fases 4 y 5 se incluirían en esa «Tradición Grandes Murales» y las 6 y 7 se apartan formalmente de esta tradición. No obstante, esta propuesta no deja de ser un esquema inicial y el fenómeno rupestre en Baja California es muy complejo como para pensar que a esta tendencia general no le podremos añadir nuevos matices cuando se documenten un mayor número de cavidades pintadas. Las fases finales del arte rupestre de Baja California corresponden a los habitantes de la península que conocieron a los colonizadores europeos. Otra cuestión es establecer el inicio del proceso y las fases intermedias. Las fechas directas sobre los murales establecen una antigüedad que se remonta al Arcaico temprano. La fecha que consideramos fiable obtenida del puma n.º 41 de la cueva de El Ratón (4.845 ±60 BP) es coherente con este entorno de dataciones. Sin embargo, no podemos dar la cuestión por zanjada. En el futuro se deberán establecer proyectos de datación que persigan objetivos específicos. Proponemos la búsqueda de fechas radiocarbónicas que relacionen figuras de las fases de la cronología relativa que se deriva de la documentación, en espera de una coherencia que dé sentido al estudio del proceso y que, posteriormente, sea comparable con el estudio de otros murales. En el caso de El Ratón, la documentación presentada facilita el proceso de selección de figuras potencialmente interesantes para confirmar o corregir la propuesta de las fases pictóricas. 4) Análisis de la composición gráfica del mural El análisis de la composición gráfica del mural nos ha permitido identificar relaciones entre distintas figuras o elementos internos de las pinturas que hemos interpretado como códigos del lenguaje muralista. Los pintores han utilizados los motivos iconográficos, formas, colores, contactos entre figuras, relaciones de simetría, ubicación en el espacio, líneas visuales, sucesiones, actitud y posición de las figuras para crear estos códigos. Estos se manifiestan en ocasiones por su valor recurrente, otras por contraste u oposición y se hacen evidentes en la composición de manera que resultan significativos. Las relaciones codificadas permiten identificar la temática representada dentro del mismo mural, y observar diferencias de estos tratamientos entre sus distintas fases. Conforme avance el estudio de los murales podremos establecer la distribución en extensión geográfica y profundidad histórica de estos códigos y así se convertirán en un elemento para discernir el proceso histórico de los murales rupestres de Baja California. Podremos ver también cómo estos recursos se asemejan o diferencian entre las sierras de San Francisco, Guadalupe y San Borja en una visión amplia del fenómeno de los Grandes Murales. 5) Funcionalidad de la cueva de El Ratón Las cuevas pintadas de la sierra de San Francisco han sido consideradas, a menudo, como agreggaton sites. Tal como fueron definidos para el Paleolítico, estos son yacimientos donde se reúne un grupo numeroso de personas para llevar a cabo una serie de rituales y actos sociales y se caracterizan por una ocupación de mucha gente por poco tiempo. Se espera que esto se refleje de alguna manera en el sedimento arqueológico y en consecuencia quede rastro de la estacionalidad que caracteriza a estas reuniones. Por otro lado, el sitio ha de reunir unas condiciones que permitan concentrar un número importante de asistentes, abundancia de elementos rituales muebles y un panel decorado que presente elementos singulares y decoraciones genéricas. En nuestra opinión, no todas las cuevas pintadas del área de los Grandes Murales cumplían la misma función. Esta apreciación deriva de las obvias diferencias entre distintos tipos de cuevas pintadas que conocemos en las sierras de San Francisco. No es lo mismo una cueva como La Pintada con más de mil figuras, una temática muy variada, muchas fases de realización del mural y una extensión considerable, que pequeñas oquedades que pueden encontrarse en varios barrancos con un número reducido de pinturas, u otras cavidades de mediano tamaño, un mural relativamente con pocas pinturas y una temática unitaria. Pero por el momento, no tenemos unas características definidas que categoricen los distintos tipos de cueva pintada ni siquiera estos sitios de congregación. En el caso de la cueva de El Ratón hemos confrontado sus datos con los provenientes de La Pintada, La Serpiente y El Porcelano y hemos visto que participan de ciertas similitudes y diferencias significativas. En primer lugar, las cuevas de La Pintada y El Ratón son amplias y con una terraza que permite la reunión de un grupo considerable de personas. La cueva de La Serpiente es una grieta en el cantil que apenas puede albergar un número muy reducido de personas y El Porcelano es una cueva mediana sin mucho espacio para grandes reuniones. Si a estas propiedades morfológicas añadimos las características de los respectivos murales vemos que El Ratón y La Pintada comparten rasgos comunes en contraste con los casos de La Serpiente y El Porcelano. Las cuevas de El Ratón y La Pintada presentan una considerable variabilidad de rasgos estilísticos y de recursos técnicos, una paleta de colores amplia y un repertorio iconográfico extenso, a tal punto que los porcentajes son muy similares. Por el contrario, El Porcelano y La Serpiente muestran una gran homogeneidad interna de rasgos estilísticos y de recursos técnicos, una paleta de colores casi monótona y poca variabilidad iconográfica. Es decir, tienen unos rasgos formales muy homogéneos en sus respectivos murales aunque sean dispares entre sí. Por otra parte, en El Ratón y La Pintada existe un proceso de realización prolongado en el tiempo, con distintas fases pictóricas y numerosas superposiciones. Las características de cuatro cuevas pintadas no son suficientes para caracterizar sitios arqueológicos complejos como son los murales pintados de Baja California. Sin embargo, esta comparación orienta en la búsqueda de estas características. De manera provisional y presumiblemente incompleta proponemos que las características que pueden definir los lugares de congregación en la sierra de San Francisco: — Lugares amplios que permitan la reunión de un número importante de gente. — Murales que presenten una considerable variabilidad de rasgos técnicos, estilísticos, cromáticos e iconográficos. — El proceso muralista será dilatado en el tiempo y mostrará diferentes fases. — Probablemente presentarán un tema principal que se complementará en las sucesivas etapas pictóricas y, en algunos casos, se añadirán nuevos temas. Distintos a estos grandes santuarios, podemos encontrar sitios con pinturas que respondan a una temática muy particular, realizados en un momento histórico concreto sin que el uso más o menos continuado del sitio haya requerido ampliar o modificar el mural. Pensamos que corresponden a lugares donde se han celebrado rituales más privados o que han sido pintados por algún motivo muy concreto. Por lo que se refiere al sedimento arqueológico, hemos de advertir que en las cuevas pintadas de estas sierras la potencia estratigráfica es pobre y que el número de excavaciones de que disponemos es escaso. Por eso no nos atrevemos a predecir cómo sería este sedimento en relación con las cuevas pintadas en lugares de congregación. En todo caso, diremos que en El Ratón no hemos identificado disposiciones de material significativas más allá de una concentración del material en hilera paralela a la pared, y que sí hemos documentado unas estructuras de combustión peculiares en cuanto a su función, que pensamos que están relacionadas con los rituales que se llevaron a cabo en este santuario rupestre. Hemos de añadir que la temática representada la cueva de El Ratón muestra una serie de relaciones con temas mitológicos documentados etnográficamente en el entorno cultural, lo que permite una propuesta interpretativa del mural en relación con aspectos astronómicos ligados a los solsticios y, por lo tanto, a la mitología de la renovación estacional y mantenimiento de la periodicidad. Esta propuesta precisa de un estudio más detallado que incluya observaciones in situ en los periodos señalados —especialmente durante el solsticio de verano— y cálculos arqueoastronómicos que abarquen los periodos históricos que nos interese documentar. Para finalizar, presentamos este trabajo del mural de El Ratón como un elemento a tener en cuenta en el estudio global de los Grandes Murales y con la esperanza de crear discusión al respecto. Consideramos que para avanzar necesitamos documentaciones exhaustivas de los murales y el análisis individualizado de los mismos para poder, luego, contrastarlos. Para ello es necesario desarrollar metodologías de documentación que permitan comparaciones parangonables. En este empeño seguiremos trabajando.
The archaeological site of El Ratón Cave: A painted cave in the Sierra de San Francisco (Baja California Sur, Mexico). The painted mural. Albert Rubio i Mora In a previous proposal of this work, we set out five aims which have been developed throughout the present research. These are described below. 1) Recording of the mural painting The visual recording of the mural painting consisted of making a digital carbon copy of the mural using the Photoshop software and with aid of the DStrech plugin. Using this visual record, we have identified 194 motifs of various classes, animal figures, humans, schematic and abstract designs, scattered over five sections in the cave. All of these motifs have been reproduced to scale on the general copy and located in the planimetry of the cave. Additionally, we have compiled a special database for researching the rock art of the Baja California central mountain ranges, or sierras. The aim is to create a resource of standardised descriptions that will allow researchers to compare the formal qualities of the motifs at both the intra- and inter-site levels. In this study, we have included the description of the database and its use, as well as documentation of the data from El Ratón Cave in individual records for each figure. 2) The creation process of the mural The work of recording the painted mural has been useful to establish the order of superimposition of the overlapping figures, which has revealed a chromatic stratigraphy. Determining the order of superimposing images is not without its problems, particularly due to the difficulty of perceiving the pigment background, the colour overlay, and the repainting and modification of the motifs. Using this information, we have been able to establish the sequence of the creation process of the mural. To reconstruct this process, we have also taken into account the composition and formal properties of the figures. The result reveals seven consecutive phases of the painting process. We have detailed the aspects of the record upon which the reconstruction of the work process is based so that it can be assessed. We suggest more specific studies that include making thin prints of some mural sections to corroborate the superimpositions. Finally, we have contrasted our proposal of sequential painting phases at El Ratón with the phases suggested by R. Viñas for La Pintada. We concluded that certain forms which characterize the consecutive phases at La Pintada follow the same pattern at El Ratón. This is better appreciated in the evolution of the profile of the bodies and the position of the quadruped’s feet. 3) Chrono-cultural context For a long time, the Great Murals were considered a relatively homogeneous phenomenon linked to the Comondú culture, which belongs to the latter period of the Baja Californian prehistory. According to the observations made in several rock art sites, our research team noticed that the sequential pictorial phases of some of the panels seemed to contradict that initial assumption and showed that, to the contrary, the painting tradition of the central mountain ranges of Baja California had a long time depth. The recording of La Pintada by R. Viñas and our own research at El Ratón corroborate the hypothesis that there are different painting events in the mural tradition which reflect cultural changes in a long diachronic process. R. Viñas has distinguished various internal phases within the Great Murals. Based on the analysis at La Pintada, he has suggested four Great Mural phases, one pictorial period that includes novel motifs that keep to the elements of the Great Murals, which he has called Great Mural Tradition, and a final phase dominated by schematic and abstract motifs, which is formally removed from the Great Murals. This scheme coincides with our observations at El Ratón, where phases 1 to 3 clearly correspond with the Great Murals, phases 4 and 5 belong to the Great Murals Tradition, and 6 to 7 move away from that tradition. Nevertheless, this proposal is only an initial scheme and the rock art of Baja California is too complex to think that this trend will remain unchanged as more painted sites are recorded. The final phases of the rock art of Baja California belong to the peoples that inhabited the peninsula when the European pioneers arrived. A more pressing issue is to establish the age of the initial and intermediate phases. The direct dates obtained from the paintings suggest an age going back to the early Archaic. The most reliable date, obtained from figure no. 41, the puma, at El Ratón Cave (4,845 +60 BP) is coherent with the range of those dates. However, the issue is not completely resolved. Future dating projects should have well-defined aims. We suggest that radiocarbon dates should concentrate on relating specific figures to the phases of the relative chronology derived from our observations, in order to make sense of the creation process and create a data set that may be compared across mural sites. In the case of El Ratón, our recording can help towards the selection of motifs that could be used for sampling, to test the sequence of pictorial phases. 4) Analysis of the mural’s visual composition The analysis of the visual composition of the mural has thrown light on the associations among figures or internal elements of the paintings, which we interpret as the codes of the mural’s language. To create such codes, the artists seem to have used the iconographic motifs, forms, colours, image overlaps, symmetry relations, location in space, visual lines, sequences, attitude and situation of the motifs. These codes may be identified by their recurrence, contrast, or opposition and become evidently meaningful in the total composition. The codified associations allow us to identify the themes represented in the mural and to distinguish differences between those associations across the various phases. As the research of the murals moves forward we will be able to establish the geographical distribution and historical depth of such codes so that they will become a component that will aid in clarifying the history of the Great Murals of Baja California. We may also be able to observe whether the codes are similar or different across the sierras of San Francisco, Guadalupe and San Borja, in order to obtain a general picture of the Great Mural phenomenon. 5) The function of Cueva del Ratón The painted caves of sierra de San Francisco have often been considered as ‘aggregation sites’. These type of sites, initially defined for the European Palaeolithic, are locations where a numerous group of people convene to carry out a series of rituals and social activities. Thus, they are characterized by a short but intensive occupation. This would somehow be reflected in the archaeological record, leaving some traces of the seasonality that generally typifies such gatherings. Furthermore, the aggregation site should comply with certain conditions to allow the concentration of a large number of attendants, and it should contain portable ritual objects and decorated panels that show singular elements and general motifs. In our opinion, not all painted caves in the region of the Great Murals had the same function. This observation is based on the obvious differences between the various types of painted caves that are known in Sierra de San Francisco. For example, a cave like La Pintada – with over a thousand figures, varied themes, a mural with several creation phases and a large extension – is not the same as the small crevices scattered across the various cliffs with only a few paintings, or the medium-sized rock shelters that contain panels with relatively few figures and one theme. For now, we do not have a fixed set of criteria to categorise the different types of painted caves, or the aggregation sites. In the case of El Ratón Cave, we have contrasted our data against the data from the sites of La Pintada, La Serpeinte and El Porcelano, and we have been able to observe certain meaningful similarities and differences. First, the caves of La Pintada and El Ratón are big and both have a gallery that would allow the gathering of a large group of people. La Serpiente cave is a cliff crevice that can allow access to only a small number of people, and El Porcelano is a medium-sized cave with not much space for a gathering. If these morphological characteristics are seen side by side with the properties of each site’s paintings, we observe that El Ratón and La Pintada share several common traits , whereas this is not the case with La Serpiente and El Porcelano. The caves of El Ratón and La Pintada both show a considerable range of stylistic properties and techniques, an extensive colour palette and iconographic repertoire, to the point that their percentages are quite similar. In contrast, El Porcelano and La Serpiente show a great internal homogeneity of stylistic properties and techniques, an almost monotone colour palette, and little iconographic variety. That is to say, the formal properties of each site’s paintings are very homogeneous, although very different between them. Furthermore, El Ratón and La Pintada reflect a long creation process with different painting phases an numerous superimpositions. The characteristics of just four painted caves are not enough to embody the complex archaeological phenomenon that is the Great Mural rock art of Baja California. However, our observations can guide our search for such criteria. Provisionally and presumably incompletely, we suggest certain characteristics that may define the aggregation sites in the sierra de San Francisco: - Large sites that allow the gathering of a great number of people. - Murals that show considerable variability of techniques, styles, colours, and motifs. - The creation process will have a long time depth and will show several work phases. - Are likely to depict a main theme that will be expanded upon in successive painting stages, and in some cases, new themes will be added. In contrast to the large sanctuaries, there are sites with paintings that portray a singular theme, painted in one single historical moment. Even if these sites were sometimes used continuously over time their murals were not extended or modified. We think that these sites may have been used to celebrate more private rituals or were painted with a very particular aim. Regarding the archaeological sediment, we must point out that the painted caves of the Baja Californian sierras have a poor stratigraphy and the number of excavations has been scarce. For this reason, we can not make any suggestions as to how the sediment of the painted caves would differ from that of aggregation sites. In any case, we will mention that at El Ratón we have not been able to identify any relevant accumulation of archaeological material apart from a concentration of objects aligned to the cave wall. We also recorded some peculiar combustion structures whose function, we believe, may be related to the rituals that were carried out at this rock sanctuary. In addition, the theme depicted at El Ratón Cave has a series of similarities with mythological subjects documented in the ethnography of the cultural region. This allows us to suggest an interpretive reading of the mural in regards of astronomical topics related to the solstices, and consequently to the myth of the seasonal rebirth and cyclic continuity. This suggestion requires a more detailed study that should include in situ observation of the mentioned dates – especially, the summer solstice- and archaeoastronomic calculations that include the historical period we want to research. --- Finally, we present this study of El Ratón mural as a contribution to the global study of the Great Murals, and with it we hope to open a scholarly discussion. We believe that to move forward in this field we need extensive records of the murals and an individual analysis that can be tested afterwards. To this aim we need to develop recording methods that allow us to make reasonable comparisons. We will keep working towards that end.

Après les catastrophes territoriales que le Mexique a subies au cours du XIXème siècle, le législateur mexicain a imposé une série de restrictions sévères sur la possession et la propriété des biens immobiliers sur les côtes et les frontières. Ces restrictions sont décrites dans l'article 27 de la Constitution Politique des États-Unis Mexicains, où il est signalé qu'aucun étranger ne peut avoir domaine directe de la terre dans une bande couvrant cinquante kilomètres de la côte et cent kilomètres de la frontière. Historiquement, toutefois, la propriété étrangère dans la zone restreinte a été toléré et même encouragé par des mécanismes juridiques tels que le fidéicommis sur des biens immobiliers en zone restreinte et les sociétés commerciales, de sorte que maintenant la côte mexicaine, particulièrement la péninsule de la Basse Californie, est dans un processus de reterritorialisation qui fait que tous les jours la terre passe aux mains d'étrangers et les côtes deviennent une zone d'exclusion. À travers de cette étude interdisciplinaire, on essayera de comprendre l'impact de ce processus sur la société péninsulaire et l'évolution du phénomène migratoire Nord-Sud qui se produit au Mexique
After the territorial disaster Mexico suffered during the nineteenth century, the Mexican legislature imposed a series of tough restrictions on the possession and ownership of real estate both on coasts and borders. These restrictions are stated in the Article 27 of the Political Constitution of the Mexican United States. This Article stipules that no foreigner can have direct ownership of land in a strip comprising fifty kilometers from the shoreline and one hundred kilometers from the border. Historically, however, foreign ownership in restricted zones has been tolerated and even encouraged through legal mechanisms such as the Trust for Real Estate in the Restricted Zone and through Corporations. As a result of this, now, the Mexican coast, particularly in the peninsula of Baja California, is in a process of re territorialization. During this process, the land becomes property of foreigners and the coasts become Zone of Exclusion. Through an interdisciplinary study, we will try to understand the effects that this process has on the peninsular society and the evolution of the North -South migration phenomenon that occurs in Mexico
Tras los desastres territoriales que México sufrió durante el siglo XIX, el legislador mexicano impuso una serie de fuertes restricciones a la posesión y propiedad de bienes inmuebles tanto en costas como en fronteras. Estas restricciones se encuentran señaladas en el artículo 27 de la Constitución Política de los Estados Unidos Mexicanos, en donde se estipula que ningún extranjero podrá tener dominio directo de la tierra en una franja que abarca cincuenta kilómetros a partir de la línea costera y cien kilómetros a partir de la línea fronteriza. Sin embargo, históricamente la propiedad extranjera en zona restringida ha sido tolerada e incluso fomentada a través de mecanismos jurídicos como el Fideicomiso de Bienes Inmuebles en Zona Restringida y las Sociedades Mercantiles, de tal manera que actualmente el litoral mexicano, en particular el de la península de Baja California, se encuentra en un proceso de reterritorialización al pasar cotidianamente a manos de extranjeros y convertirse las costas en zona de exclusión. A través de un estudio interdisciplinario se intentarán comprender los efectos que este proceso tiene sobre la sociedad peninsular así como la evolución del fenómeno migratorio Norte-Sur que se presenta en México

This thesis discusses both theoretical and practical considerations inherent in conducting community-based research within a case study of sea turtle conservation in Baja California, Mexico. A brief background, including the general ecology, status and distribution of sea turtles of the Baja peninsula is presented, with an overview of the current and historic use and management of sea turtles. Several sets of theories provide the context within which the case example is analyzed. A discussion of how concepts of "science" and "knowledge" are shaped and how these perceptions impact choices made in natural resource management and planning is presented. This includes a brief discussion of conservation ethics and conservation rationale, as well as a review of the debates surrounding indigenous knowledge and its application in conservation. A review of community-based efforts in sea turtle conservation is also presented. The data and analysis offered in this thesis is the result of two field seasons working as a member of an interdisciplinary sea turtle conservation team: conducting biological studies, surveys, informal and semi-structured interviews and participant observation. The major goal of this research project was to evaluate a people-oriented approach to conservation. The objectives of the Baja sea turtle conservation project included: the involvement of fishing communities in the development of conservation projects, the involvement of local students and fishermen in the collection of data and the public sharing of research results on a regular basis. Results of this case study suggest that through dependence on the host community for food, equipment, labor and guidance a special connection was established, fostering trust and building the partnerships necessary for long-term conservation success. For this reason, fishermen and other members of the local host communities were more willing to cooperate with outsiders and share their intimate knowledge of their environment - including information on the daily movements and distribution of sea turtles. It is crucial that the fishermen feel empowered before they choose to participate in the sea turtle conservation efforts. They must be viewed, and view themselves, as an integral part of the conservation team contributing valuable knowledge and ideas, not just acting as boat drivers and guides for outside researchers within the host community. Community meetings served as an outlet to voice concerns and share information. The active involvement and participation of local communities is a highly effective tool in the sea turtle conservation efforts in the region.
Graduation date: 2002

abstract: The historic Cacachilas mining district is located in Baja California Sur, approximately 20 kilometers east of La Paz, and has a series of gold- and silver-hosted veins, faults, and shear zones within Cretaceous granodioritic plutons. The remote geographic location and past political events within Mexico left the district essentially unexplored after the late 1800s, when the Mexican Revolution began. More recent discovery of gold deposits along the Baja peninsula instigated a renewed interest in mineralization in the Sierra Cacachilas. The area lacks detailed previous geologic data, so this study focused on characterizing the controls of mineralization and the locations of mineralized trends of deposits within the northeastern Sierra Cacachilas, with a goal toward helping assess economic viability of the deposits. I mapped surficial geologic data, such as outcrop locations, alteration assemblages, limonite intensities, and structural measurements. I then synthesized these into geologic maps and cross sections. I combined field data with geochemical assays and structural plots to better characterize individual historic district trends and newly located trends to understand the distribution of mineralization at surface and at depth. Lastly, I synthesized geology of the Sierra Cacachilas with other gold and silver deposits located in the southern Baja peninsula to better characterize the mineralization and deposit style of the Cacachilas district. Mineralization in the northeastern Sierra Cacachilas is mainly restricted to steeply dipping quartz veins, faults, and brittle-ductile shear zones that trend generally northeast. Some veins are en-echelon within the mineralized zones, implying some lateral movement along the zones. Veins are dominated by milky to clear quartz with trace sulfides, abundant limonite (after sulfides), and local open-space textures. Mineralization is interpreted to be intermediate between classic epithermal and mesothermal veins. Within mineralized trends and commonly associated with mineralization are greisen-like zones that are defined by intense sericitic to muscovitic overprint, trend northeast, and are with or without sulfides. The intensity of sulfide abundance and limonitic alteration after sulfides within and near mineralized zones is overall a good guide to mineralization. Based on past reports and on my recent studies, the Cacachilas district has very promising potential for relatively small, high-grade deposits.
Dissertation/Thesis
Masters Thesis Geological Sciences 2015

This dissertation explores the potential of renewable energy and efficiency strategies to solve the energy challenges faced by the people living in the biosphere reserve of El Vizcaíno, which is located in the North Pacific region of the Mexican state of Baja California Sur. This research setting provides a practical analytical milieu to understand better the multiple problems faced by practitioners and agencies trying to implement sustainable energy solutions in Mexico. The thesis starts with a literature review (chapter two) that examines accumulated international experience regarding the development of renewable energy projects as a prelude to identifying the most salient implementation barriers impeding this type of initiatives. Two particularly salient findings from the literature review include the importance of considering gender issues in energy analysis and the value of using participatory research methods. These findings informed fieldwork design and the analytical framework of the dissertation. Chapter three surveys electricity generation as well as residential and commercial electricity use in nine coastal communities located in El Vizcaíno. Chapter three summarizes the fieldwork methodology used, which relies on a mix of qualitative and quantitative research methods that aim at enabling a gender-disaggregated analysis to describe more accurately local energy uses, needs, and barriers. Chapter four describes the current plans of the state government, which are focused in expanding one of the state’s diesel-powered electricity grids to El Vizcaíno. The Chapter also examines the potential for replacing diesel generators with a combination of renewable energy systems and efficiency measures in the coastal communities sampled. Chapter five analyzes strategies to enable the implementation of sustainable energy approaches in El Vizcaíno. Chapter five highlights several international examples that could be useful to inform organizational changes at the federal and state level aimed at fostering renewable energy and efficiency initiatives that enhance energy security, protect the environment, and also increase economic opportunities in El Vizcaíno and elsewhere in Mexico. Chapter six concludes the thesis by providing: a summary of all key findings, a broad analysis of the implications of the research, and an overview of future lines of inquiry.

Geologic features at the western edge of the Gulf Extensional Province (GEP) in northeastern Baja California, Mexico, record details of Pacific-North American (PAC-NAM) plate boundary history prior to and during its establishment within the Gulf of California. Methods of study in Santa Isabel Wash (SIW) (informally named) in the northern Sierra Santa Isabel include geologic mapping of ~140 km^2 (1:20000 scale) along the northern margin of the Miocene-Pliocene Puertecitos Volcanic Province (PVP), ^(40)Ar/^(39)Ar geochronology, electron microprobe analysis, paleomagnetic study, and petrography. Local Neogene stratigraphy (spanning ~17-6 Ma) includes volcaniclastic breccias, basaltic to dacitic lava flows, and rhyolitic pyroclastic flow deposits. The completeness of the lithologic package improves stratigraphic correlations between the PVP and nearby regions. High-angle extension-related faults cut all rocks in SIW. The southeastward projection of the pre-6 Ma Matorni accommodation zone, which separates a northern region of greater and more prolonged extension from a less extended southern zone, may pass on the north side of SIW. Paleomagnetic analysis indicates no vertical axis rotations in SIW since 6 Ma. This contrasts with regions north of the Matomi accommodation zone where clockwise rotation has accompanied extensional deformation since 3-6 Ma. About 500 meters of post-6 Ma, E-side-down displacement occurs across two major, NNW-striking normal faults on the west side of SIW. These, and smaller synthetic and antithetic faults in the hanging walls, accommodate up to 4% E- to ENE-directed extension. Quaternary deformation is also documented. A new model developed to explain ENE-directed extension in northeastern Baja California partitions present-day PAC-NAM plate motion between NNW-striking, sinistral dip-slip faults and N- to NNW-striking, dextral (oblique?) strike-slip fault(s) in the northernmost Gulf of California. The model offers explanations for the geometry of plate motion accommodation between the latitudes of the Agua Blanca fault and the PVP, bathymetric features near Wagner and Consag basins, the position and jumps of nearby spreading centers since 6 Ma, the greater width and bend in coastline of the northernmost Gulf of California, the incorporation of the PVP into the GEP 2-3 Ma, and suggests a transitional tectonic scenario between oceanic spreading centers and continental transforms ("Wagner Transition Zone").