Download or read book Postglacial Timberline Fluctuations La Plata Mountains Southwestern Colorado written by Kenneth L. Petersen and published by . This book was released on 1976 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Deglaciation and Postglacial Treeline Fluctuation in the Northern San Juan Mountains Colorado written by Paul E. Carrara and published by . This book was released on 2011 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: The San Juan Mountains of southwestern Colorado contain numerous lakes and bogs at and above treeline. In June 1978, Lake Emma, a tarn above present-day treeline, was suddenly drained by the collapse of underground mine workings. This study was initiated because the draining exposed a well-preserved archive of subfossil coniferous wood fragments that provided a unique opportunity to further our understanding of the paleoclimatic history of this region. These paleoclimatic studies--coniferous macrofossil identification in conjunction with radiocarbon dating, deuterium analysis of the dated conifer fragments, as well as pollen and fossil insect analyses--yielded new information regarding Holocene climate and accompanying treeline changes in the northern San Juan Mountains. This report synthesizes previously published reports by the author and other investigators, and unpublished information of the author bearing on late Pleistocene and Holocene treeline and climate in this region. Retreat of the glacier that occupied the upper Animas River valley from its Pinedale terminal position began about 19.4±1.5 10Be thousands of years ago and was essentially complete by about 12.3±1.0 10Be thousands of years ago. Two sets of late Pleistocene cirque moraines were identified in the northern San Juan Mountains. The older set is widespread and probably correlates with the Younger Dryas (11,000-10,000 radiocarbon years before present; 12,800-11,500 calendar years). The younger set is found only in the Grenadier Range and represents remnant glacier ice lying in well-shaded niches in a mountain range undergoing rapid deglaciation. A snowbank at the northern base of this range appears to be fronted by a Little Ice Age moraine. Soon after deglaciation the average July temperature is estimated to have been about 5°C cooler and timberline about 650 meters lower than at present. However, timberline (and treeline) responded rapidly to the postglacial warming and reached higher-than-present elevations by the early Holocene. A comparison of recently obtained accelerator mass spectrometry radiocarbon ages of coniferous wood fragments from Lake Emma, previously dated by conventional radiocarbon methods during the 1980s, led to a slight modification of previously published ages of Holocene treeline fluctuations. As early as 9,200 radiocarbon years before present (about 10,400 calendar years) and probably to about 5,400 radiocarbon years before present (about 6,200 calendar years), treeline was at least 80 meters higher than at present (about 3,660 meters). Furthermore, a large conifer fragment with a complacent annual ring record suggests that timberline may have been at least 140 meters higher than present (about 3,600 meters) about 8,000 radiocarbon years before present (about 8,900 calendar years). These past elevations of treeline and timberline suggest that growing-season temperatures were at least 0.5°-0.9°C warmer than at present. Deuterium data from the Lake Emma wood samples suggests that the maximum average temperature change from about 9,000 to 5,400 radiocarbon years before present (about 10,150 to 6,200 calendar years) was about 4°C. Owing to these warmer temperatures the summer monsoon circulation, which currently brings a large part of the annual precipitation to the San Juan Mountains, probably was more intense during the early and middle Holocene than it is today. Between about 5,400 and 3,500 radiocarbon years before present (about 6,200 and 3,770 calendar years) it appears that treeline was near its present-day limit. After 3,500 radiocarbon years before present (about 3,770 calendar years), evidence of treeline position is very sparse, suggesting that treeline lay at, or below, its present-day elevation. However, a spruce krummholz fragment from the Lake Emma site provided two radiocarbon ages of about 3,100 radiocarbon years before present (about 3,300 calendar years). It is not clear whether this wood fragment represents a short-lived climatic amelioration or whether it was from a unique individual that grew above the general treeline at that time. Approximately 20 other studies at sites throughout western North America that have yielded records of conifer remains above present-day limits are presented in the appendix of this report. The results of many of these studies are similar to those obtained in this study and indicate a higher than present-day treeline during the early to middle Holocene. Because this study is based on more than 100 radiocarbon ages, including 66 ages from 53 coniferous wood fragments from the Lake Emma site, as well as pollen and insect analysis and deuterium data from the wood fragments, this study represents one of the best-documented records of Holocene treeline fluctuations in North America.

Download or read book Archaeological Resources of Southwestern Colorado written by and published by . This book was released on 1982 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geological Survey Bulletin written by and published by . This book was released on 1979 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sierra Ecology Project written by and published by . This book was released on 1978 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sustainable Lifeways written by Naomi F. Miller and published by University of Pennsylvania Press. This book was released on 2012-02-24 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sustainable Lifeways addresses forces of conservatism and innovation in societies dependent on the exploitation of aquatic and other wild resources, agriculture, and specialized pastoralism. The volume gathers specialists working in four areas of the world with significant archaeological and paleoenvironmental databases: West Asia, the American Southwest, East Africa, and Andean South America, and contributing to research in three broad time scales: long term (spanning millennia), medium term (archaeological time, spanning centuries or a few thousand years), and recent (ethnohistoric or ethnographic, spanning years or decades). By bringing an archaeological eye to an examination of human response to unpredictable environmental conditions, informed by an understanding of contemporary traditional peoples, the contributors to this volume develop a more detailed picture of how societies perceive environmental risk, how they alter their behavior in the face of changing conditions, and under what challenges the most rapid and far-reaching changes in adaptation have taken place. Sustainable Lifeways enhances our understanding of both the forces of conservatism and innovation which may have been in play in major transitions in the past, such as the development of complex society, and the expansions of early empires. Studies present examples of cattle herders in East Africa, hunter-gatherers and pastoralists in the Levant, South American fisher/farmers, and farmer/hunters of the U.S. Southwest.

Download or read book The Outlier Survey written by Robert P. Powers and published by . This book was released on 1983 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Archeological Excavations at the Pontiac Pit Site written by Terri L. Liestman and published by . This book was released on 1984 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Late Quaternary Environments of the United States written by Herbert Edgar Wright and published by U of Minnesota Press. This book was released on 1983 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Arctic and Alpine Research written by and published by . This book was released on 1997 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Agriculture Handbook written by and published by . This book was released on 1996 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: Set includes revised editions of some issues.

Download or read book Dwarf Mistletoes written by Frank G. Hawksworth and published by DIANE Publishing. This book was released on 1998-04 with total page 427 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents: generalized life cycle; sexual reproductive biology; mechanism and trends of evolution; biogeography and paleogeographic history; host relationships; ecological relationships; biotic associates; host-parasite physiology; anatomy of the dwarf mistletoe shoot system; endophytic system; pathogenic effects; control; systematics: philosophy, problems, and criteria for classification; molecular systematics; formal taxonomy. Extensive bibliography. Scientific and common names; collecting and curating techniques; herbaria consulted; specimens examined; glossary; subject and species indexes.

Download or read book Excavation of Two Anasazi Sites in Southern Utah written by and published by . This book was released on 1981 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The two reports published here contain elements which contribute substantially to this broader spectrum of Southwestern cultural change. While primarily descriptive in nature, these two site reports, one from the western Kayenta area and one from the margin of the Mesa Verde area and the eastern Kayenta, suggest that the changes which occurred in the more centralized portions of these regions were directly related to what happened on the margins. That, while the site densities and population aggregates may not have been as high, the same factors affected these marginal areas. That conclusion could be expected, but what may not be expected is the differential response which appears to have occurred. After reading these two reports, it appears that it may be possible to discern elements of change in these fringe areas that, once defined, will provide new insight into what happened and why and in what are presently the better known areas of the Southwest. These two papers are important, in sum, not only because they are reports of work in poorly known areas, but because they do provide analyses of fringe areas, they help us to understand the Southwest generally"--From preliminary introduction.

Download or read book The Colorado Plateau II written by Charles Van Riper and published by University of Arizona Press. This book was released on 2005 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: The publication of The Colorado Plateau: Cultural, Biological, and Physical Research in 2004 marked a timely summation of current research in the Four Corners states. This new volume, derived from the seventh Biennial Conference on the Colorado Plateau in 2003, complements the previous book by focusing on the integration of science into resource management issues. The 32 chapters range in content from measuring human impacts on cultural resources, through grazing and the wildland-urban interface issues, to parameters of climate change on the Plateau. The book also introduces economic perspectives by considering shifting patterns and regional disparities in the Colorado Plateau economy. A series of chapters on mountain lions explores the human-wildland interface. These chapters deal with the entire spectrum of challenges associated with managing this large mammal species in Arizona and on the Colorado Plateau, conveying a wealth of timely information of interest to wildlife managers and enthusiasts. Another provocative set of chapters on biophysical resources explores the management of forest restoration, from the micro scale all the way up to large-scale GIS analyses of ponderosa pine ecosystems on the Colorado Plateau. Given recent concerns for forest health in the wake of fires, severe drought, and bark-beetle infestation, these chapters will prove enlightening for forest service, park service, and land management professionals at both the federal and state level, as well as general readers interested in how forest management practices will ultimately affect their recreation activities. With broad coverage that touches on topics as diverse as movement patterns of rattlesnakes, calculating watersheds, and rescuing looted rockshelters, this volume stands as a compendium of cutting-edge research on the Colorado Plateau that offers a wealth of insights for many scholars.

Download or read book Packrat Middens written by Julio L. Betancourt and published by University of Arizona Press. This book was released on 2021-11-16 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past thirty years, late Quaternary environments in the arid interior of western North America have been revealed by a unique source of fossils: well-preserved fragments of plants and animals accumulated locally by packrats and quite often encased, amberlike, in large masses of crystallized urine. These packrat middens are ubiquitous in caves and rock crevices throughout the arid West, where they can lie preserved for tens of thousands of years. More than a thousand of these deposits have been dated and analyzed, and middens have supplanted pollen records as a touchstone for studying vegetation dynamics and climatic change in radiocarbon time (the last 40,000 years). Now, similar deposits made by other mammals like hyraxes are being reported from other parts of the world. This book brings together the findings and views of many of the researchers investigating fossil middens in the United States, Mexico, Africa, the Middle East, and Australia. The contributions serve to open a forum for methodological concerns, update the fossil record of various geographic regions, introduce new applications, and display the vast potential for fossil midden analysis in arid regions worldwide. The findings presented here will serve to foster regional research and to promote general studies devoted to global climate change. Included in the text are more than two hundred charts, photographs, and maps.

Download or read book Bibliography of Geology and Hydrology San Juan Basin New Mexico Colorado Arizona and Utah written by Ann Finley Wright and published by . This book was released on 1979 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Timberline written by Stephen F. Arno and published by Mountaineers Books. This book was released on 1984 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: Originally published in 1984, this is a classic in Western natural history now made available again to climbers, hikers, and other enthusiasts.