SOILS IN THE GLACIATED HEADWATERS OF SOUTH
FORK ASHLEY CREEK, UINTA MOUNTAINS, NORTHEASTERN UTAH
DOUGLASS, Daniel C., and MUNROE, Jeffrey
S., Department of Geology and Geophysics, 1215 W. Dayton St., Madison WI
53706, dcdougla@students.wisc.edu and jmunroe@geology.wisc.edu
Eighteen soils were described and sampled in the South Fork of Ashley
Creek drainage during August 1997. Vegetation in the study area is
subalpine coniferous forest dominated by Pinus contorta, Picea engelmanii,
and Abies lasiocarpa. Elevations range from 2710 to 3331 m asl.
Soils were described on several glacial landforms, including outwash, hummocky
lateral moraines, kames, and ground moraine. Based on the position
of the soils with respect to moraines mapped by Atwood (1909), two of the
soils may be of Holocene age, 15 of Pinedale, and one of pre-Pinedale age.
Parent materials include basal till, outwash, secondary flow tills, ice
contact stratified drift, and lacustrine sediments. Soil subgroups
include Typic Cryochrepts, Typic Cryorthents, Typic Cryumbrepts, and Typic
Cryoboralfs. Typic Cryochrepts are by far the most numerous soils
in the area, comprising half of the soils examined.
All soils are poorly developed, reflecting the pedogenic inertia
of the resistant till derived from the quartzitic bedrock. Most of
the soils have a textural discontinuity between a silt loam surface horizon
of varying thickness (12-31 cm), overlying sandier glacial sediment at
depth. This surface horizon is interpreted as a loess cap.
Preliminary results suggest there is no correlation between age of the
surfaces and the thickness of the loess cap. This situation implies
that the onset of loess deposition postdates the formation of the youngest
moraines. Alternatively, loess deposition may have been continuous
throughout the late Quaternary with rates of erosion and deposition of
loess balanced at the locations we sampled.