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The upland soils of Randolph County, Indiana were studied for the following purposes: to provide an additional characterization of these soils, to identify a set of soil parameters that could delineate the extent of Late Wisconsinan glaciation in that county and to determine if there were any geographic trends in silt cap thickness. The study was prompted from observations by the recent Randolph County Soil Survey team that high clay content soils commonly associated with the county's Late Wisconsinan till (Lagro Formation) were found south of its previously mapped boundary.The only soil parameters that were effective in mapping the extent of Late Wisconsinan glaciation were: particle size analyses and some combinations of particle size analysis data with other soil parameters. The data support the previously mapped boundary of the Late Wisconsinan sediments in Randolph County, Indiana.Silt cap thickness was identified to be greatest in three areas of the county. However, the source(s) of these silts could not be determined. / Department of Geology

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This study reconstructs vegetation and climate encompassing pre-full glacial and Holocene time for the Mogollon Rim region of Arizona. Implications for the southwestern United States are discussed. Pine species (some currently disjunct) or species groups are identified. Two lakes were cored, the sediments were analyzed for pollen content, and dates were obtained by radiocarbon analysis. Hay Lake (2780 m) is surrounded by mixed conifer forest in the White Mountains, Arizona (34°N and 109°30'W). Jacob Lake (2285 m, 34°25' N and 110°50' W) is surrounded by ponderosa pine forest. Extrapolated dates for basal sediments are approximately 42,000 B.P. and 20,000 B.P. for Hay Lake and Jacob Lake respectively. Based on pollen, local vegetation at Hay Lake between approximately 42,000 and 29,000 B.P. consisted of mixed conifer forest dominated by Pinus aristata, P. flexilis and/or P. strobiformis with Picea codominant. Of the identified pine species, 98% are haploxylon and most are pinyon pine. Pinyon pine was more widespread at lower elevations than today. The proposed 1 Mid-Wisconsin climate has greater winter precipitation and summers cooler than today. However, the climate was warmer and probably drier than the full-glacial. Treeline was above the site. The period 29,000 to 25,000 B.P. is climatically and vegetationally transitory to the full glacial. Yellow pines (p. ponderosa/contorta) are present for the first time and Picea pollen increases from previous levels. The full glacial (25,000 to 13,700 B.P.) at Hay Lake is characterized by an association of Picea and Gramineae pollen and at Jacob Lake by Picea and Artemisia pollen. A high elevation parkland at the forest-tundra ecotone surrounded Hay Lake. Open coniferous forest surrounded Jacob Lake. A conservative estimate of treeline depression is 570 m. Winters during the full glacial were warmer and wetter and summers were cooler and drier than today. The early and middle Holocene is characterized by an increase in open vegetation and in herbaceous pollen taxa; Artemisia at Hay Lake and Gramineae at Jacob Lake. The climate was cooler and wetter than today but less so than during the Pleistocene. Iron-mottled sediments and a hiatus in the pollen record at Jacob Lake (between about 11,850 and 900 B.P.) together with expansion of Artemisia at Hay Lake represent overall drought during the middle Holocene when compared with today although summer monsoons may have been intensified. Modern pollen assemblages begin at Hay Lake about 1700 B.P. and are not datable at Jacob Lake. The transition to modern conditions may have resulted from increased fire frequency at Hay Lake and from fire suppression by early settlers at Jacob Lake.