Brady Soil Research Articles

Radiocarbon ages on late pleistocene loess stratigraphy of Nebraska and Kansas, Central Great Plains, U.S.A.

In the central Great Plains of the United States, radiocarbon dating of loess and buried soils is clarifying the late Quaternary loess chronology for the period 25,000 to 10,000 BP. Along Harland Lake, Nebraska, a soil developed in the Gilman Canyon Formation and overlain by Peoria Loess has radiocarbon ages on soil humates of 30,700 to 21,500 BP. At one site, two Picea charcoal bands in the lower meter of Peoria Loess have radiocarbon ages of 21,250 and 19,730 BP. Therefore, in the vicinity of Harlan Lake, deposition of Peoria Loess apparently began around 21,000 BP. Peoria Loess deposition appears to have been interrupted by an episode of river entrenchment prior to 12,600 BP. Spring activity shortly thereafter suggests that incision was coeval to an increase in effective moisture. The termination of Peoria Loess deposition is marked by the Brady Soil, which in the Harlan Lake area has radiocarbon ages on soil humates of 11,800 to 10,200 BP. Comparison of the Harlan Lake chronology with chronologies completed elsewhere in the central Great Plains reveals general synchrony among periods of pedogenesis and Peoria Loess deposition. Little is known, however, about vegetation conditions in the region when loess was accumulating. Charcoal has been noted chiefly in the basal Peoria Loess, suggesting that some trees were present during initial Peoria Loess deposition. The extent of this tree cover is unknown, however. Charcoal is rare in the middle and upper Peoria Loess.

The Brady soil and subdivision of post-Sangamonian time in the Midcontinent region

The Brady soil and subdivision of post-Sangamonian time in the Midcontinent region

SEQUENCE OF ALLUVIATION ALONG THE LOUP RIVERS, VALLEY COUNTY AREA, NEBRASKA

Research Article| November 01, 1955 SEQUENCE OF ALLUVIATION ALONG THE LOUP RIVERS, VALLEY COUNTY AREA, NEBRASKA ROBERT D MILLER; ROBERT D MILLER U. S. GEOLOGICAL SURVEY, ENGINEERING GEOLOGY BRANCH, DENVER FEDERAL CENTER, DENVER, COLORADO Search for other works by this author on: GSW Google Scholar GLENN R SCOTT GLENN R SCOTT U. S. GEOLOGICAL SURVEY, ENGINEERING GEOLOGY BRANCH, DENVER FEDERAL CENTER, DENVER, COLORADO Search for other works by this author on: GSW Google Scholar GSA Bulletin (1955) 66 (11): 1431–1448. https://doi.org/10.1130/0016-7606(1955)66[1431:SOAATL]2.0.CO;2 Article history received: 14 Feb 1955 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation ROBERT D MILLER, GLENN R SCOTT; SEQUENCE OF ALLUVIATION ALONG THE LOUP RIVERS, VALLEY COUNTY AREA, NEBRASKA. GSA Bulletin 1955;; 66 (11): 1431–1448. doi: https://doi.org/10.1130/0016-7606(1955)66[1431:SOAATL]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Alluviation along the North and Middle Loup rivers in Valley County, Nebraska, produced a series of alluvial silt beds on which are developed five interstadial soils of Brady (?), Cary and Mankato (?), Mankato (?), early Recent and late Recent age. No deposits of Illinoian age were found and in at least one place the Brady (?) soil is superposed on a gleyed horizon developed on the Sappa formation, which overlies the Grand Island formation. Post-Yarmouth erosion removed the Sappa formation and part of the Grand Island formation at most places. The characteristic Sangamon soil was not developed on uneroded remnants of the soil of Yarmouth age because of a wet, poorly drained environment. A large collection of molluscs obtained from this gley soil supports stratigraphic evidence indicating a Yarmouth age.Alluviation during the glacial substages of Wisconsin time and soil formation during the interglacial substages were uninterrupted by erosion until after development of the soil of Mankato age. The Wisconsin deposits were dissected to below the Brady soil in places, and the resulting gullies were filled with later alluvium. The late Recent fill terrace lies 15 feet below the top of the late Wisconsin terrace. Subsequent cutting and filling in late Recent time produced another terrace 11 feet below the older terrace. The modern gully was cut during the last century. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

ROCKY MOUNTAIN AND CONTINENTAL PLEISTOCENE DEPOSITS IN THE WATERTON REGION, ALBERTA, CANADA

Continental drift of probable Cary age overlies Early Wisconsin and Late Wisconsin mountain drift in the Rocky Mountain piedmont of the Waterton region, Alberta, Canada. On the basis of geomorphic relations and soil profiles the Early Wisconsin moraines are correlated with the Iowan and Tazewell, and the Late Wisconsin moraines with the Cary. An older, deeply weathered drift (Kennedy drift) on remnants of the high-level Flaxville erosion surface is correlated with the Kansan. There are marked differences in the profiles of weathering developed on drifts correlated with the Kansan, Iowan-Tazewell, and Cary. A buried soil, named the Drywood soil, which occurs on Early Wisconsin mountain drift below the continental drift, is tentatively correlated with the Brady soil of the Middle West. A series of proglacial lakes, formed as the continental ice withdrew down drainage, are reconstructed on the basis of shoreline features and outlet channels. Periglacial features are represented by natural mounds and involuted zones. Postglacial deposits include: (1) colluvium and a volcanic ash layer assigned to the Xerothermic period, and (2) cirque moraine, gravel fans and valley gravels, and a buried peat bed assigned to the Little Ice Age. The peat bed has a radiocarbon age of 3261 ± 250–3327 ± 320 years. In general the Pleistocene record suggests that glacial maxima in the mountains were essentially synchronous with the Kansan, Iowan-Tazewell, and Cary maxima of the Keewatin ice sheet in the western part of the continental interior.

Stratigraphic Zonation of the Peoria Loess in Kansas

An extensive thick sheet of generally calcareous, fossiliferous occurs at or near the surface in northern, central, and southwestern Kansas. This loess, the Peoria silt member of the Sanborn formation in Kansas classification, lies above the Sangamon (Loveland) buried soil and includes at the top the Brady buried soil, hitherto of uncertain age. The history of the term Peorian loess is reviewed, and the age of the Peoria is considered in the light of published reports. Three zones are recognized in the Peoria in Kansas: (1) a basal zone, devoid of molluscan fossils; (2) a lower molluscan faunal zone; and (3) an upper molluscan faunal zone. On stratigraphic and faunal evidence the basal zone is correlated with the Farmdale of Illinois, the lower zone with Iowa loess, and the upper zone with Tazewell loess. The Brady soil is shown to have been formed in post-Tazewellian-pre-Caryan (or pre-Mankatoan) time, designated the Bradyan interglacial interval.

Use of Fossil Soils in Kansas Pleistocene Stratigraphy

Fossil soils, or buried profiles of weathering, have for many years been known to occur at various positions in the stratigraphic column. The factors controlling the development of soil profiles and the environmental implications of the several distinctive morphological types have been extensively discussed in the soils science literature and summarized in easily accessible form (U. S. Dept. Agr., 1938). Nevertheless, this tool of far reaching value to the stratigrapher has only recently been generally applied to problems of stratigraphic correlation, classification, and interpretation of the late Cenozoic deposits of the Great Plains region. The work of Kay and Pierce (1920) attracted attention to the use of fossil soils as a means of regional correlation of glacial tills, but these workers made use of only one type of soil profile (gumbotils) developed on a till plain under conditions of poor drainage. They were not concerned with the transition of profile morphology to correlary soils developed on other materials, or under different conditions of drainage, climate, and floral cover. Leighton and MacClintock (1930) used fossil soils in a broader sense by recognizing in weathering profiles at the same stratigraphic position morphologic differences caused by different conditions of drainage or erosional history. In Nebraska fossil soils have been used far beyond the glacial border (Lugn, 1935; Condra, Reed, and Gordon, 1947; Schultz and Stout, 1948) and one of them serves as an important stratigraphic datum over the State. Within the past half dozen years fossil soils, or buried profiles of weathering, have been used widely as a means of correlation and classification of the Pleistocene deposits in Kansas (Frye and Fent, 1947). Fossil soils have been found at the contact of all major stratigraphic subdivisions, and two of these soils have been traced extensively over the State. Weathering profiles have been studied on Nebraska and Kansas glacial tills in the northeastern part of the State; on the Sappa member of the Meade formation; on the Loveland silt member of the Sanborn formation (Loveland soil or Sangamon soil) from the Missouri bluffs to the Colorado State line and from Nebraska to Oklahoma; and on the Peoria silt member of the Sanborn formation (Brady soil) over a region almost as great. Fossil soils have value not only as stratigraphic markers but also as indicators of paleo-ecology. Pleistocene soils in the Great Plains region are generally well preserved. Their form and character can be compared