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As part of an archaeology study on the Fort Bliss Military Reservation in west Texas, [Hall et al. (2010)][1] reported optically stimulated luminescence (OSL) dates from two backhoe trenches referred to as localities 100 and 200. In both trenches, a sedimentary unit termed “Q3” was designated

The title compounds, N-(4-bromophenyl)-5,6-dichloronicotinamide, C 12 H 7 BrCl 2 N 2 O, and 6-chloro-5-fluoro-N-(3-pyridyl)nicotinamide, C 11 H 7 ClFN 3 O, crystallize as almost planar molecules held together by intermolecular hydrogen bonding. The dichloro compound shows C-Cl distances of 1.69 (2) and 1.725 (15)A at C6 and C5, respectively. These compounds are representatives of a class of compounds biologically important as herbicidal, pesticidal or fungicidal agents.

Companion to Memior 39. This supplement, which was prepared for a field trip in conjunction with an international meeting of soil micromorphologists, presents additional information for many of the original Desert Project study areas and presents new information for five additional study areas. Major changes in the classification of the Aridisols were made in 1994; the new system and its relation to the old one are shown.Illustrative soils and landscapes range in age from late Holocene to late Pliocene. Photomicrographs in color include a variety of argillans and calcitans, evidence for dissolution of primary grains, silica nodules that post-date argillans in an ancient pipe, and both clay formation and illuviation in a soil formed in bedrock.The five additional study areas are located on detailed soil maps and include sites illustrating (1) formation of the stage IV carbonate horizon and its radiocarbon chronology, the first to be reported in the world literature on genesis of soil carbonate; (2) profound changes in carbonate morphology (stage III to IV) associated with change in particle size; (3) a rare bedrock-defended, ancient fan and soil in Ice Canyon of the Organ Mountains; (4) a scarplet terrain in high-carbonate sediments where argillic horizons have formed in late Pleistocene soils but not in Holocene soils; and (5) a middle Pleistocene soil with evidence for dissolution of silicate grains by pressure solution, for precipitation of calcite by microorganisms, and for neoformation of palygorskite.When the Desert Project began in August 1957, one of the problems for study concerned the origin of horizons of silicate clay accumulation. At the time, the prevailing opinion was that horizons of clay accumulation in desert soils formed by weathering in place. This view was still common well into the 1960s. Thin section studies are one way of learning more about the origin of these horizons. Thin sections showed that nearly all bed surfaces and pores lacked clay skins in the arid part of the study area, pipes being the only exception. Instead, coatings of oriented clay on sand grains and pebbles were found to be characteristic of the Bt horizons. Field studies, laboratory analyses, and thin sections all indicate that the red to brown horizons of silicate clay accumulation in the Desert Project area contain illuvial clay. A summary of Bt horizons and evidence for illuviation is presented in the Desert Project Guidebook.Photomicrographs illustrate illuvial clay and carbonate in soils that range in age from late Holocene to middle to early Pleistocene. Coatings of oriented clay on sand grains and pebbles are characteristic of the Bt horizons. Grain argillans of many Bt horizons have been partly to completely obliterated by carbonate. Calcified root hairs, calcite filaments, and framework grain coatings are the youngest forms of carbonate accumulation. They are currently forming and are the major morphological expression of carbonate in late Holocene soils. Progressively older carbonate forms increase in density and hardness with increasing carbonate content. Thin sections show evidence of dissolution of primary grains in soils of late middle Pleistocene age and older. Companion to Memoir 39.

The oxygen isotopic ratios (expressed as parts per thousand relative to mean ocean water, SMOW, delta/sup 18/O) of the quartz from 13 soils undergoing much wind erosion during the study period of 1972-1975 in four southwestern states and from comparison areas were determined. The delta/sup 18/O for quartz from eight Texas (TX) and Arizona (AZ) soils range from 13.0 to 15.9 /sup 0///sub 00/. The quartz of the sands and silts coarser than 20 ..mu..m from three of the soils had delta/sup 18/O values ranging from 13.1 to 15.1 /sup 0///sub 00/, characteristic of an ultimate igneous-metamorphic origin. The delta/sup 18/O values increase greatly with decreasing particle size of quartz from three soils ranging from loamy fine sand to loam to clay in texture. The delta/sup 18/O of the 1-10 ..mu..m quartz fraction (aerosol size) ranged from 19.2 to 20.2 /sup 0///sub 00/ (19.55 +- 0.28 /sup 0///sub 00/; +- sigma) for the thirteen soils most affected by dust storms. The oxygen isotopic ratios of 1-10 ..mu..m quartz from three Hawaiian soils and two sediments from Lake Waiau occurring at 3,970 m altitude on the Mauna Kea summit on the Island of Hawaii give a delta/sup 18/O mean of 18.3more » +- 0.2 /sup 0///sub 00/.« less

Radiocarbon ages have been obtained from seven buried charcoal horizons in a desert area of southern New Mexico. Several deposits of highly calcareous alluvium range in age from less than 1,100 to somewhat greater than 5,000 years and are therefore of Recent age. Pleistocene deposits much older than 5,000 years also occur. Pleistocene soils of adjacent topographic highs were a major source of the Recent sediments. Evidence in this area indicates that the present climate is warmer and drier than the Pleistocene pluvial climates. This change to a drier and warmer climate could have decreased the vegetative cover in places and started strong erosion of Pleistocene soils in these areas. The dated charcoal also establishes a maximum, and in some instances a minimum age for several soils formed in the deposits. With increasing age of soil during Recent time, the progression of soil development appears to have been marked by development of an A horizon, destruction of thin sedimentary strata, slight accumulation of carbonate, development of structure in materials of sufficiently fine texture, and, with continued carbonate accumulation, development of a weak calcic horizon. In contrast, soils of Pleistocene age can have distinct argillic horizons and strong horizons of carbonate accumulation. It is postulated that the wetter climates of Pleistocene pluvials, associated with greater vegetative cover and landscape stability, were required for development of argillic horizons in these highly calcareous parent materials.

This book is intended primarily for use in field-study tours of the Desert-Soil Geomorphology Project of the U.S. Soil Conservation Service (informally termed the Desert Project) in Dona Ana County, southern New Mexico. Main purposes are to illustrate major soils and landscapes of the project area, to illustrate principles of soil and landscape evolution in basin-and-range topography, to show the landscape positions in which the soils are most likely to occur, to describe soil development, and to illustrate the United States system of soil taxonomy as it applies to desert soils of the region.The Desert Project encompasses a 400-sq mi area near Las Cruces and includes a segment of the Rio Grande valley and parts of adjacent intermontane basins. Soil Survey Investigations field and laboratory studies were initiated in 1957; work was done in cooperation with the New Mexico State University College of Agriculture and the New Mexico Bureau of Mines and Mineral Resources. It represents one of the most comprehensive studies of soils and landscapes ever undertaken in an arid to semiarid region. The Desert Project is similar to many other areas in terms of terrain, soil parent materials, range in age of soils, and general climatic and geologic history. Thus principles of soil and landscape evolution worked out at the Desert Project will have widespread application. A number of formal field-study tours were held during progress of the research, and the Desert Project has proved to be of valuable study and training ground for a variety of professional workers and students. Field trip participants have included agronomists, anthropologists, biologists, foresters, geomorphologists, geologists, hydrologists, range scientists, and soil scientists. Numerous requests have been received for copies of previous field guides that are out of print. These were printed only in limited numbers and were much less comprehensive in scope than the present volume, which is intended to serve as permanent guide to many of the detailed study sites of the Desert Project.Field investigations included mapping the soils, geomorphic surfaces, and surficial deposits at a scale of 1:15,840. In addition, detailed studies at larger scales were conducted along selected transects. Joint laboratory and field investigations included studies of characteristics and genesis of a number of soils and soil horizons, radiocarbon dating of pedogenic carbonates and organic carbon, and studies of the effect of additions from dustfall to soil genesis and morphology. Since 1965, project investigations have been done in cooperations with the New Mexico Bureau of Mines and Mineral Resources; and since 1967, all major reports on geologic phases of the project have been published either by or with support of the Bureau. In 1977 the Desert Project became a formal part of the Bureau's environmental geology program, which includes sponsorship of this and future field-study tours.The Desert Project has been a good study and training ground for a wide variety of workers. The project area is similar to many arid and semiarid regions in terms of terrain, parent materials for soil, range in age of soils, and general climatic history. Thus principles of soil and landscape evolution worked out in the Desert Project also apply to many areas other than the southwest United States. A number of formal field-study tours were held during progress of the research. In addition to this memoir and several journal articles written during progress of the research, the Desert Project soil monograph has been written on the project as a whole, which may be attained from the National Technical Information Service. Complete laboratory analyses, details for methods of analyses reported in this book, many pedon descriptions, a list of all soils observed in the project area, and a detailed map of the entire project area may be found in this monograph. A final report on late Cenozoic geology of the project will be written after detailed mapping of the bedrock areas is complete. Companion to Bulletin 142.

In the southern Rio Grande rift, two extensional regimes of different origin (but transitional with each other through the Miocene) can be interpreted from structures and rocks formed within the past 28 to 29 m.y. The earlier regime, which began about 28 to 29 m.y. B.P., is characterized by emplacement of “basaltic andesite” flows with relatively high strontium isotope ratios; formation of broad, relatively deep, northwest-trending basins; and incipient uplift of some of the region9s fault-block mountains. This regime appears to have developed in a back-arc setting, perhaps behind a rapidly steepening slab and a westward-sweeping arc system. The younger episode seemingly represents a renewal or acceleration of block faulting and volcanism during the latest Miocene and Pliocene, 9 to 3 m.y. B.P., after a long transitional period during the early and mid-Miocene when volcanism was absent and tectonism was less vigorous. The latest Miocene-Pliocene episode produced the modern northerly-trending rift basins and uplifts, regional uplift of the rift 1 to 2 km above sea level, and renewal of volcanism, this time dominated by relatively primitive alkali-olivine basalt. New basalt dates reveal that in the southern rift, modern ranges and basins were almost fully developed and that near-modern drainage ways were established across uplifts into bolsons by about 5.0 m.y. B.P. An ancestral Rio Grande had extended itself southward into the southern rift by 3 to 4 m.y. B.P., and the river entrenched itself into its modern valley between 0.7 and 0.5 m.y. B.P. Horst-graben development of the southern Basin and Range province, as well as associated basaltic volcanism, swept progressively eastward from southeastern California in the past 20 m.y., culminating in formation of the Rio Grande rift and other fault-block terrane in west Texas, New Mexico, and northern Chihuahua in the latest Miocene and Pliocene. Late Quaternary Basin and Range fault scarps increase in density eastward, which also suggests that more easterly parts of the province are youngest. These relationships support a previous model of an eastward-expanding, slab-free triangle (related to growth of the San Andreas transform), through which mantle upwelling triggers eastward-younging patterns of tectonism, volcanism, and uplift and promotes lithospheric thinning and increased heat flow. Across most of the southern Basin and Range and Rio Grande rift, the horst-graben structures related to growth of this triangle are superimposed on somewhat older (late Oligocene-middle Miocene) extensional terrane that appears to have formed in a back-arc or arc setting.