Search USGS⌕ Search

Geology topics

Steven M. Colman

Publications and source records attributed to Steven M. Colman.

82 records · Page 5Linked to original sources
USGS1985

Map showing upper Cenozoic rocks and deposits and Quaternary faults, Rio Grande rift, south-central Colorado

This map shows the faults and faulted rocks and deposits in the tectonically active part of the Rio Grande rift in Colorado, with particular emphasis on faults and deposits of Quaternary age. The Rio Grande rift in Colorado has been the subject of considerable recent geologic investigation. General compilations of the late Cenozoic tectonic features of the state of Colorado have been made by others. More detailed work used in compiling the map is shown in figure 1.

Colorado↗
USGS1983

Ages estimated from a diffusion equation model for scarp degradation

The diffusion equation derived from the continuity equation for hillslopes is applied to scarp erosion in unconsolidated materials. Solutions to this equation allow direct calculation of the product of the rate coefficient and the age of the scarp from measurements of scarp morphology. Where the rate coefficient can be estimated or can be derived from scarps of known age, this method allows direct calculation of unknown ages of scarps.

Science↗
USGS1983

Preliminary surficial geologic map of the Fisher Valley-Professor Valley area, southeastern Utah

This map was constructed to document the distribution and character of the late Cenozoic deposits in the Fisher Valley-Professor Valley area. The map area includes the central portion of one of the long northwest-trending salt-cored anticlines of the Paradox Basin. The map area contains Fisher Valley, formed by collapse of a portion of the crest of the anticline, and the Onion Creek salt diapir, a cupola of salt on the main diapiric salt mass.

Utah↗
USGS1982

Clay mineralogy of weathering rinds and possible implications concerning the sources of clay minerals in soils

Weathering rinds on volcanic clasts in Quaternary deposits in the western United States contain only very fine grained and poorly crystalline clay minerals. Rinds were sampled from soils containing well-developed argillic B horizons in deposits about 10 5 yr old or more. The clay-size fraction of the rinds is dominated by allophane and iron hydroxy-oxides, whereas the B horizons contain abundant, well-crystallized clay minerals. The contrast between the clay mineralogy of the weathering rinds, in which weathering is isolated from other soil processes, and that of the associated soil matrices suggests a need to reassess assumptions concerning the rates at which clay minerals form and the sources of clay minerals in argillic B horizons. This study suggests that crystalline clay minerals form more slowly in weathering rinds than is generally assumed for soil environments and that the weathering of primary minerals may not be the dominant source of crystalline clay minerals in middle to late Pleistocene soils.

Geology↗
USGS1976

Erosional landform map of the Redwood Creek drainage basin, Humboldt County, California, 1947-74

Landslides and actively eroding stream channels disrupt roads, damage valuable timberland, and increase stream sediment loads in northwestern California. This 1:62,500 photointerpretative map shows the distribution of ten common types of fluvial and mass-movement erosional landforms in the drainage basin of Redwood Creek in 1947 and 1974. The mapped landforms include slides, slumps, large compound earthflows, debris avalanches, unstable streambanks and adjacent hillslopes, small mass-movement features, questionable or inactive landslides, deeply incised amphitheater shaped drainage basins, small actively eroding water courses, and actively eroding main channel stream banks. The map legend describes these landforms and the techniques used in preparing the map. The amount and diversity of erosional activity increased greatly between 1947 and 1974. This increased activity apparently reflects major floods in 1953, 1955, 1964, and 1972, as well as the start of large scale, tractor-yarded clearcut timber harvest in the basin. (Woodard-USGS)

California↗