The tertiary history of the Chiricahua volcanic field of southeastern Arizona is essentially that of rhyolitic ash-flow deposition and concomitant block faulting in the period from 29 to 25 m.y., as determined by K-Ar analysis. The Rhyolite Canyon ash-flow sheet is the youngest of three sheets, each more than 1000 feet thick. Its distribution is limited mainly to the Chiricahua and northern Pedregosa Mountains with a lesser amount of deposits in the neighboring Swisshelm and Peloncillo Mountains. It is estimated that the original areal extent was of the order of 700 square miles and that the volume of deposits was around 100 cubic miles. The source area of the Rhyolite Canyon sheet is identified as a 13-mile diameter caldera, named the Turkey Creek caldera. This is the first major caldera of the Valles type described in the Mexican Highland and Sonoran Desert sections of the Basin and Range. It is unique because of its denudation. Erosion to 5000-foot depth locally has exposed thick sections of moat deposits and a fine grained monzonite pluton associated with central doming. Rhyolite Canyon tuff in the caldera, some 3000 feet thick, is domed and intruded by the monzonite. More than 1500 feet of tuff breccia, tuffaceous sediments, and rhyolite flows are exposed in the moat, along with 3000 feet of monzonite forming annular segments a couple miles wide abutting or overlying rocks forming the caldera wall. The most monzonite is similar to that in the dome and was emplaced amidst the period of deposition in the caldera. Petrographic and trace element analyses indicate a cogenetic relation between the Rhyolite Canyon sequence and the moat rhyolites. The K-Ar age of the Rhyolite Canyon tuff is very close to that of the monzonite. The ash-flow sheet immediately underlying the Rhyolite Canyon sheet is also very close in age as indicated by K-Ar analyses. Block faulting and tilting took place between the two sheets and also following the deposition of the Rhyolite Canyon sheet. There is evidence that the present basin-range structure was not established until after the Rhyolite Canyon sheet had been emplaced.

The majestic mountains of the uKhahlamba Drakensberg, formed many millennia ago were home to the Bushmen[footnote 1] or San people. They lived at these mountains for thousands of years before they were colonised by the Bantu speakers and the Europeans. Academic writings for many years have perpetuated the thinking that Bushman people were largely extinct. The dominance of this view in the academic writings was encouraged by historical evidence that Europeans and Bantu speakers hunted and killed Bushmen over the last several centuries. Researchers argue that the extermination of the Bushmen was because they were less human in the eyes of the foreigners, due to cattle raiding. There is still some element of this thinking amongst today’s academics, although research in the last decade is questioning this thinking. The question of whether descendants do exist is relevant to issues of rights of access to ancestral sacred sites, in particular rock art sites. At present, access to rock art sites is granted on qualification as an authentic fee-paying tourist (or affordability) rather than on group rights to a cultural heritage resource (cultural rights). Based on this, I argue that access to rock art sites is based on qualification rather than by right. This is largely driven by an approach that emphasises the physical conservation and financial sustainability of a site, rather than its spiritual maintenance. It has become clear that the interests in rock art by tourists and Bushman descendants are distinct from each other. Tourists have an aesthetic significance for rock art while Bushmen descendants have a spiritual significance for the paintings. Beyond any doubt, the physically based and financially driven approach has brought new challenges to today’s Bushmen descendants, whom in reaffirming their identities now have a new challenge to overcome. Not only are the rock art sites physically threatened but also they have lost much of their spiritual powers. Their fate lies in the hands of heritage officers who must determine access rights to the painted shelters. Both the National Heritage Resources Act and the KwaZulu-Natal Heritage Act acknowledge living heritage. However, the existence of this heritage is judged against the physical approach to rock art management. If the practises of descendants are perceived to be a threat to the rock art, they will not be approved. The case of the Duma is a classic example. Prior to the ritual ceremony at Game Pass Shelter, Kamberg, they were informed of the minimum standards for opening a rock art site to public and rules of how people should behave while visiting painted shelters. While it was evident that there are problems with the two approaches, the spiritual and physical approach, discussed in the thesis, it is important that solutions are identified. I do not believe that one approach on its own will be good enough, for reasons discussed in the thesis. Instead, the two approaches should be implemented together to compliment each other by identifying common grounds. I provide strategies as to how I believe that such a common ground can be reached. In addition, I provide my own analytical thinking as to how these strategies can be achieved. There is no general consensus over which term is appropriate. Both terms are considered by some academics to be derogatory or pejorative (Chennels 2003). San means vagabond and was given to the Bushmen by Khoi-Khoi people, because they considered themselves of a better social class, as they had domesticated animals and were more sedentary than Bushmen. However, according to WIMSA (Thoma 2003) the word San is derived from the Hai||om language meaning “people who gather”. It is normally written Saan but it has been accepted to write San. In 1993 the San requested to be called San when referred to as an entire group. If one refers to individual people/groups they like to be called by their language and cultural name i.e. Khwe, !Kung, !Xun, Ju|’hoansi, ‡Khomani, N|u, |’Auni, Hai||om, etc In this thesis, Bushmen is a preferred term, because it is a better-known term among the people who are central to this study. It is used without any insulting connotations attached to the term.

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Charon's Garden Wilderness Area within the Wichita Mountains National Wildlife Refuge in Oklahoma is a landscape that is granted federal protection through the Wilderness Act of 1964. The discourse of wilderness management is influenced by governmental policies and practice which organize knowledge surrounding the natural landscape, like with the formation and semantics of the Wilderness Act. The Wilderness Act establishes characteristics that are designed to monitor and control the landscape and serve as a baseline and criterion for further wilderness preservation. These characteristics render the wilderness space as governable. Conservation management alternatives are identified which bypass the duality of nature from western society suggested by the discourse of environmental policy. These alternatives are understood under two notions of behaviors and perceptions. The project's goal is to uncover wilderness users' recreation behaviors and perceptions of wilderness as a designated space. Through understanding and assessing user's behaviors and perception of wilderness, alternative policies and practices that offer sustainable management practices and recreation opportunities can be developed.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1981. / Microfiche copy available in Archives and Science. / Vita. / Includes bibliographies. / by Steven William Roecker. / Ph.D.

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Robust interpretations of rock thermal histories are critical for resolving the timing and rates of geologic processes, especially as low-temperature thermochronology has become a common tool for investigating the evolution of landscapes and mountain belts and the feedbacks between geodynamic processes. Most interpretations of thermochronologic cooling ages, however, attribute rock cooling entirely to rock exhumation - a common but tenuous assumption in many settings where thermochronology is used to investigate links between tectonics, climate, and landscape evolution, because these places often have history of magmatism. Exploring the complexities - and advantages - of interpreting low-temperature thermochronologic data in magmatic terranes is the principal theme of this work. Using simple analytical approximations as well as the finite-element code Pecube, we characterize the cooling age patterns inside and around plutons emplaced at upper and middle crustal levels and identify the advective and conductive scaling relationships that govern these patterns. We find that the resetting aureole width, the difference between reset and unreset cooling ages in country rocks, and the lag time between pluton crystallization age and pluton cooling age all scale with exhumation rate because this rate sets the advective timescale of cooling. Cooling age-elevation relationships in these steadily exhuming models have changes in slope that would masquerade as changes in exhumation or erosion rates in real datasets, if the thermal effects of the plutons were not accounted for. This is the case both in the country rocks immediately next to upper crustal plutons and, surprisingly, in the country rocks kilometers above mid-crustal plutons with no surface expression. Together with a lag-time analysis useful for the practical question of when it is appropriate to interpret a cooling age as an exhumation rate in crystalline rocks, this work improves our framework for evaluating the effects of magmatism on thermochronologic datasets. We also demonstrate the importance of considering the magmatic history of a region in field studies of the Colorado Plateau, where interpreting apatite (U-Th)/He data requires diagnosing significant inter- and intra-sample age variability. Prior to considering the thermal history of the region, we develop a new model for a common source of this age variability: excess He implantation from U and Th (i.e., eU) hosted in secondary grain boundary phases (GBPs), which can make very low eU apatites hundreds of percent 'too old'. Samples significantly affected by He implantation are not useful for thermal history interpretations, but this model does provide a diagnostic tool for discriminating these samples from those with useful age trends. Once the effects of GBPs have been accounted for, the remaining data from two different thermochronologic archives in the central Colorado Plateau provide a new perspective on the Cenozoic history of the region, which has a multiphase - and enigmatic - history of magmatism and erosion. We find that sandstones in the thermal aureoles around the Henry, La Sal, and Abajo mountains intrusive complexes were usefully primed by magmatic heating in the Oligocene to document the subsequent late Cenozoic history of the region more clearly than any other thermochronologic archive on the Plateau. These data document a stable Miocene landscape (erosion rates<30 m/Ma) that rapidly exhumed ~1.5-2 km in the Plio-Pleistocene (~250-700 m/Ma no earlier than 5 Ma) in the Henry and Abajo mountains, and strongly suggest most of this erosion occurred in the last 3-2 Ma. The integration of the Colorado River ca. 6 Ma, which dropped regional base-level, is the principal driver of this erosion. It is likely, however, that a component of the rapid Pleistocene rock cooling is unique to the high mountains of the Colorado Plateau and reflects an increase in spring snow-melt discharge during glacial periods. Although apatite thermochronology results far from the Oligocene intrusive complexes cannot resolve this detailed Plio-Pleistocene history, they do constrain the onset of late Cenozoic erosion to no earlier than ~6 Ma. Moreover, apatite cooling ages from these rocks also document Oligocene cooling (ca. 25 Ma) that is contemporaneous with the emplacement of the laccoliths and the waning of the vigorous magmatic flare-up that swept through the southwestern USA ca. 40-25 Ma. Although the cooling ages are consistent with ~1 km of exhumation in the late Oligocene and early Miocene, as previous workers have suggested in the eastern Grand Canyon region, we demonstrate that a transient change in the geothermal gradient (peaking at ~50˚C/Ma in the late Oligocene) driven by moderate mid-crustal magmatism can produce identical age patterns. Therefore, we re-interpret the mid-Cenozoic erosion event on the Colorado Plateau as primarily a change in the crustal thermal field, rather than an erosional event. This requires a more significant Laramide-age unroofing in parts of the central Plateau and perhaps a re-evaluation of the interpretations of Oligocene canyon cutting in the Grand Canyon region