PHYSICAL AND CHEMICAL EVIDENCE FOR EOLIAN ADDITIONS TO SUBALPINE SOILS IN THE EASTERN UINTA MOUNTAINS, NORTHEASTERN UTAH
     MUNROE, Jeffrey S., and DOUGLASS, Daniel C., Department of Geology & Geophysics,
University of Wisconsin, Madison, 1215 West Dayton Street, Madison WI, 53706-1692, jmunroe@geology.wisc.edu, and dcdougla@students.wisc.edu
The results of lab analyses of soil samples from eighteen subalpine pedons in the eastern Uinta Mountains support field interpretations of a textural discontinuity in soil parent materials.  A total of 72 samples collected in 1997 were analyzed for particle size distribution (with sand fractionation), easily oxidizable organic C, total N, extractable P, NH4OAc extractable bases, cation-exchange capacity, and exchangeable acidity.  Previous reports of soils with multiple parent materials in the region were based solely on field observations.  Soil subgroups represented in this study include Typic Cryochrepts (56%), Typic Cryorthents (22%), Typic Cryumbrepts (11%), and Typic Cryoboralfs (11%).
Sixteen of the 18 pedons contain surface horizons enriched in silt.  The silt caps range from 6-31 cm thick with a mean thickness of 15.8 cm and a standard deviation of 6.5.  Silt contents in the caps range from 33 to 55% with a mean of 45% and a standard deviation of 6.4.  Silt contents in the underlying soil horizons average 26%.
 The silt cap has previously been interpreted as an eolian deposit.  Chemical analyses of these samples provide additional evidence for eolian inputs to the soils.  In particular, concentration of base cations in soil samples are much greater than those measured in representative samples of the Uinta Mountain Group quartzites.  Concentrations of Ca, Mg, Na, and K in the bedrock are all less than 1% as determined by XRF analysis (reported as oxides).  Yet base saturation in all 18 pedons investigated ranges from 15% to 53% with an average of 40%.  Ca is the most abundant base cation with an average concentration of 5.8 meq/100g.
 Despite this evidence for cation enrichment in the subalpine soils, total base saturation is lower than that reported for nearby alpine soils.  This discrepency requires further study and may reflect more intense base cycling by subalpine vegetation, or an inequality in primary loess deposition across the alpine/subalpine ecotone.