English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Soils formed on glaciofluvial terraces of Rock Creek, southwest of Billings, Mont., yield information on rates of soil development under controlled conditions of parent material, vegetation, and relief. Three chronosequences of soils on seven terraces, which range in age from 7 to 2,000 ka (thousands of years before present), reflect the modern decrease in precipitation with decreasing altitude. Some soil properties indicate paleoclimate and test current models of climate during the last glaciation. The ages and glaciofluvial origin of the terraces, including, from youngest to oldest, the Holocene (nonglacial), Pinedale, Bull Lake, Boyd, Lower Roberts, Upper Roberts, and Mesa terraces, have been established by using several methods. The dating methods include correlation with dated deposits in West Yellowstone, Mont., tephrochronology, streamincision rates, and comparison to the marine oxygenisotope record. The Pinedale and Bull Lake terrace deposits are glaciofluvial because they merge with glacial moraines within the mountains. The Lower Roberts terrace gravel is probably glaciofluvial because it appears to have formed contemporaneously with a pre-Bull Lake till. The glaciofluvial origin of deposits of the Boyd, Upper Roberts, and Mesa terraces is inferred because these gravels resemble in form and thickness those of known glaciofluvial deposits. Soil properties of total texture, pH, and color, expressed on a numeric scale, show statistically significant correlations with age for all the soils studied. The texture, color, and clay films of soils in the wetter environment at the mountain front develop at logarithmic rates. Soils older than 20 ka from the drier basin climate exhibit linear rates of change with time in pH, color, and texture, but the younger soils appear to develop at logarithmic rates. The pH of mountain-front soils decreases over time, whereas that of drier soils increases. Logarithmic rates of development in mountain soils are probably controlled by near-surface weathering processes, whereas linear rates of development in drier soils may be controlled by influx of eolian dust. Evidence of permafrost conditions, periodic dissolution of CaCO 3 in the drier soils, and depths of pedogenic clay demonstrate a substantial increase in available moisture during glaciations, owing primarily to a decrease of evapotranspiration due to lower temperatures. The soils farthest downstream have CaCOg morphology that, assuming a 10 °C decrease in mean annual temperature, suggests a concomitant decrease in actual precipitation. The changing position of the boundary between calcic and noncalcic soils on each terrace may reflect either increasing wetness of recent interglaciations or soil conditions induced by periodic leaching and precipitation of CaCOg near the boundary.

Soils in granitic alluvium in humid and semiarid climates along Rock Creek, Carbon County, Montana