[ { "id": "authors:xffcg-p7728", "collection": "authors", "collection_id": "xffcg-p7728", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200225-070100542", "type": "book_section", "title": "Desertification in an Arid Shrubland in the Southwestern United States", "book_title": "Land Degradation", "author": [ { "family_name": "Okin", "given_name": "Gregory S.", "clpid": "Okin-G-S" }, { "family_name": "Murray", "given_name": "Bruce", "clpid": "Murray-B-C" }, { "family_name": "Schlesinger", "given_name": "William H.", "clpid": "Schlesinger-W-H" } ], "contributor": [ { "family_name": "Conacher", "given_name": "Arthur J.", "clpid": "Conacher-A-J" } ], "abstract": "In the Mojave Desert of the southwestern U.S. human destruction of soil crusts and removal of vegetation have led to progressive, expanding degradation of adjacent arid shrublands. Aeolian mobilisation of dust, sand and litter triggered by anthropogenic disturbance contributes to the destruction of islands of fertility in adjacent areas by killing shrubs through burial and abrasion. This interrupts nutrient-accumulation processes and allows the loss of soil resources by abiotic transport. Thus the processes of degradation spread across the landscape driven largely by abiotic processes.\n\nSoil chemical analyses and remote sensing observations presented here are designed to test a model hypothesis of degradation of arid shrublands. Nutrient and non-nutrient chemical species in the soil act as tracers of material transport and provide clues as to the nature of progressive anthropogenic degradation in arid shrublands. Remote sensing yields information about short- and long-term effects on the landscape as well as important constraints on the magnitude of degradation. Field, chemical and remote sensing observations argue for an extension of recent definitions and models of desertification to include the loss of islands of fertility in established shrublands. This extended model places arid shrublands in a continuum of physical and ecological processes and ecosystems that links semiarid grasslands with Sahara-like hyperarid barren lands.", "doi": "10.1007/978-94-017-2033-5_4", "isbn": "978-90-481-5636-8", "publisher": "Springer", "place_of_publication": "Dordrecht", "publication_date": "2001", "pages": "53-70" }, { "id": "authors:wz4bd-sqm20", "collection": "authors", "collection_id": "wz4bd-sqm20", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131125-141607077", "type": "book_section", "title": "Martian oases? Feasibility of orbital thermal emission detection", "book_title": "The case for Mars VI : making Mars an affordable destination", "author": [ { "family_name": "Haldemann", "given_name": "Albert F. C.", "clpid": "Haldemann-A-F-C" }, { "family_name": "Danielson", "given_name": "G. Edward", "clpid": "Danielson-G-E" }, { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" } ], "contributor": [ { "family_name": "McMillen", "given_name": "Kelly R.", "clpid": "McMillen-K-R" } ], "abstract": "We review the motivation for searching out modem \"oases\" on Mars,\nand examine methods of detecting them from orbit. We use the term\n\"oasis\" to refer to sites with anomalous thermal behavior at, or near the\nplanet's surface. Such sites may be more likely than other locations on\nMars to have liquid water nearby, hence the terminology reminiscent of\nEarth's deserts. Three types of \"oases\" are considered here: small-scale\nvolcanic eruptions, hot springs, and subsurface intrusions. The general\nconsensus is that such oases are highly unlikely on Mars today, and\nprobably do not exist at all. How much investment is worthy of such a\nhigh-risk, unlikely return? We argue that the potential long-term importance\nof such a discovery does merit a significant investment. We propose\na detection strategy based on a high spatial resolution infra-red\nthermal emission instrument, though other techniques are briefly discussed.\nWe conclude that such an instrument could feasibly detect surface\nlavas, and quite likely any surface hot springs, but would not be\nable to unambiguously determine the presence of a buried geothermal\nanomaly that does not manifest itself sufficiently at the surface in one of\nthe two other forms.", "isbn": "0-87703-461-3", "publisher": "American Astronautical Society", "place_of_publication": "San Diego, CA", "publication_date": "2000", "pages": "267-277" }, { "id": "authors:wze48-kzc67", "collection": "authors", "collection_id": "wze48-kzc67", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150211-074844386", "type": "book_section", "title": "Pliocene-Pleistocene stratigraphy and depositional environments, southern Confidence Hills, Death Valley, California", "book_title": "Cenozoic basins of the Death Valley region", "author": [ { "family_name": "Beratan", "given_name": "Kathi K.", "clpid": "Beratan-K-K" }, { "family_name": "Hsieh", "given_name": "Jean", "clpid": "Hsieh-Jean" }, { "family_name": "Murray", "given_name": "Bruce", "clpid": "Murray-B-C" } ], "contributor": [ { "family_name": "Wright", "given_name": "Lauren A.", "clpid": "Wright-L-A" }, { "family_name": "Troxel", "given_name": "Bennie W.", "clpid": "Troxel-B-W" } ], "abstract": "Pliocene to Recent lacustrine and playa deposits in the southwestern United\nStates preserve a sedimentary record of climate change and tectonic activity. The middle\nPliocene record is particularly important, because it represents the beginning of\nthe glacial-interglacial climate that characterizes the Quaternary. However, continental\nsedimentary records of this time period arc scarce. Well-exposed playa margin\ndeposits in the Confidence Hills, southern Death Valley National Monument, California,\nwere deposited between about 2.5 and 1.5 Ma. Detailed chronometric control is\nprovided by tephrochronology and magnetostratigraphy.\n\nA new stratigraphic unit, the Confidence Hills Formation, is herein defined. This\nformation consists of interbedded tine- to coarse-grained siliciclastic strata with abundant\ngypsum and anhydrite. Ten distinct sedimentary lithofacies were defined within\nthe Confidence Hills Formation based on variations in their siliciclastic and evaporitc\ncomponents. Lithofacies dominated by siliciclastic components include the siltstone,\ntine-grained sandstone, coarse-grained sandstone, and interbedded coarse-grained\nsandstone/conglomerate lithofacies. Those dominated by evaporitic components\ninclude the halitic mudstone/siltstone/fine-grained sandstone, gypsiferous mudstone/\nsiltstone/fine-grained sandstone, banded anhydrite, and thin-bedded to massive\nanhydrite lithofacies. The siliciclastic component shows an overall coarsening- and\nthickening-upward trend, from dominantly thinly bedded siltstone in the lower part\nof the section to dominantly medium-bedded, tine- to medium-grained sandstone in\nthe upper part. Superimposed on this pattern is variation in amounts, types, and textures\nof evaporite deposits.\n\nThe lithofacies observed in the Confidence Hills arc readily interpretable using\nthe classification of saline lake subenvironments developed by Hardie et al. (1978).\nThe halitic mudstone lithofacies is interpreted as having been deposited within the\ncenter of the saline lake. The anhydrite- and gypsum-bearing lithofacies are interpreted\nas having been deposited in the saline mudflat subenvironment marginal to the\nsaline lake. The siliciclastic sediment was derived primarily from the Owlshcad\nMountains to the west and deposited by streamflood mechanisms in a distal alluvial\nfan setting.\n\nThe overall coarsening-upward sequence is interpreted as recording progradation\nof one or more marginal alluvial fans into a saline lake. The depositional rate was\nfairly constant at about 29 mm/ka. Major changes in depositional setting occurred roughly every 200,000 yr; smaller scale variations record changes occurring on time\nscales of tens of' thousands of years (evaporite-rich vs. evaporitc-poor intervals) to\nyears (individual evaporite/siliciclastic couplets). Potential causes of these variations\ninclude autocyclic changes within the marginal depositional systems (e.g., lobe switching\nwithin the alluvial fan), changes in sediment supply due to fault motion, or\nchanges in the position of the groundwater table reflecting local and/or regional climate\nvariations. Different causes likely acted at different time scales. Larger scale\nvariations do not appear to correlate with events in Searles Lake, and thus arc tentatively\ninterpreted as resulting from autocyclic or tectonic causes. Smaller scale variations\nmay record climate fluctuations. More detailed comparison with the\nsedimentary records from elsewhere in the region is required before a detailed climate\nrecord can be constructed.", "doi": "10.1130/0-8137-2333-7.289", "isbn": "9780813723334", "publisher": "Geological Society of America", "place_of_publication": "Boulder, CO", "publication_date": "1999", "pages": "289-300" }, { "id": "authors:6pb2c-k4572", "collection": "authors", "collection_id": "6pb2c-k4572", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140414-082853187", "type": "book_section", "title": "Remote Monitoring of Shifting Sands and Vegetation Cover in Arid Regions", "book_title": "IGARSS '94: International Geoscience and Remote Sensing Symposium: surface and atmospheric remote sensing: technologies, data analysis, and interpretation", "author": [ { "family_name": "Ray", "given_name": "Terrill W.", "clpid": "Ray-T-W" }, { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" } ], "abstract": "A significant factor in the degradation of arid and semi-arid lands is the removal of sand and soil through wind action. Mobilized sand can destroy downwind vegetation through sand blasting and burial. Since vegetation cover is an important factor in determining the erodibility of an area, there is a potential positive feedback that can lead ultimately to the mobilization of larger areas of sand. Mobilized areas of sand in irrigated arid regions can be detected in the visible and near-infrared because of increased albedo and the decreased plant cover, in the thermal infrared due to emissivity differences between the very loose sheet of active material and the relatively consolidated stable soils, and in the radar wavelengths because of the unusual, but theoretically predicted, polarization effects caused in radar reflection from wind-rippled surfaces. This paper focuses on the application of these techniques to the Manix Basin area of the Mojave Desert in Southern California. The Manix Basin area has been the site of extensive cultivation using center-pivot irrigation systems. Progressive abandonment of many fields since 1972 has mobilized some areas of sand. The authors have used sizable body of remote sensing data from airborne and satellite platforms to study this area along with in-situ investigations. These investigations have shown that even though arid region vegetation presents special problems for the quantitative use of remote sensing instruments, indices such as IPVI can be used to make qualitative determinations of arid region plant cover. Lower levels of Infrared Percentage Vegetation Index indicate either lower plant cover, or a shift from the stable climax community vegetation (creosote bush) to communities more typical of disturbed areas. A temporal study of this area has revealed that the sand mobilization is episodic and tending to increase in areal extent with each episode.", "doi": "10.1109/IGARSS.1994.399335", "isbn": "0-7803-1497-2", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "1994-08", "pages": "1033-1035" }, { "id": "authors:hax9n-hj504", "collection": "authors", "collection_id": "hax9n-hj504", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130116-155858832", "type": "book_section", "title": "Outcrop Geology of Plio-Pleistocene Strata of the Confidence Hills, Southern Death Valley, California", "author": [ { "family_name": "Gomez", "given_name": "F.", "clpid": "Gomez-F" }, { "family_name": "Hsieh", "given_name": "J.", "clpid": "Hsieh-Jean" }, { "family_name": "Holt", "given_name": "J.", "clpid": "Holt-J" }, { "family_name": "Murray", "given_name": "B.", "clpid": "Murray-B-C" }, { "family_name": "Kirschvink", "given_name": "J.", "orcid": "0000-0001-9486-6689", "clpid": "Kirschvink-J-L" } ], "contributor": [ { "family_name": "Beratan", "given_name": "Kathi K.", "clpid": "Beratan-K-K" }, { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Pluhar", "given_name": "Christopher J.", "clpid": "Pluhar-C-J" }, { "family_name": "Reynolds", "given_name": "Jennifer", "clpid": "Reynolds-J" } ], "abstract": "The Confidence Hills, Southern Death Valley, California, are composed of Plio-Pleistocene lacustrine beds, evaporite\nbeds, ashes, playa sediments, alluvial fan and fluvial deposits. The sediments have been divided into 5 mappable units.\nFrom oldest to youngest, they are: the Confidence Hills \"formation\u00b7 (informal) composed of three interfingering\nmembers, and overlying Units A and B which do not exhibit transitional contacts with either underlying units or with\nthemselves. The Confidence Hills formation includes the lacustrine and playa fine sands, and silts and clays of fluvial\nsediments. The lower two members are characterized by the presence of anhydrite. This formation also contains at least\n15 volcanic ashes useful for determining age and correlation. Unit B is a red-to-brown coarse fanglomerate that lies\ndisconformably above the Confidence Hills formation. Unit A, a second fanglomerate deposit, overlies the other units in\na prominent angular unconformity. The southernmost canyon was studied in greater detail, both lithostratigraphically\nand magnetostratigraphically (Beratan and Murray, and Pluhar et al., this volume). There are two primary structural\nfeatures in the Confidence Hills: the Southern Death Valley fault zone and a large anticlinorium which makes up the\nConfidence Hills.", "publisher": "San Bernardino County Museum Association", "publication_date": "1992-05" } ]