DEVELOPMENT OF A
STAGE IV CALCIUM CARBONATE SOIL AT MORMON MESA,
Amy L. Brock, Department of Geoscience, University of
Nevada, Las Vegas, Las Vegas, NV,
Pisoliths and brecciation have been
identified in soils in many locales throughout the southwestern U.S.
and world. However, the processes by
which they form are relatively unknown.
This research proposes a model of development for these features. This study focuses on highly developed petrocalcic
horizons at Mormon Mesa, Jean and Laughlin,
NV and is currently testing the
following three hypotheses: (1) Multiple processes
result in the formation of calcic soil pisoliths. (2) Multiple processes result in the
formation of brecciation that defines stage VI petrocalcic soils and the
sequence of brecciation reveals multiple cycles of landform erosion, followed
by sedimentation and renewed landscape stability. (3) The formation and development of these features
is time dependant.
This study uses micromorphology to examine pisoliths and
brecciation, minerals present and the relationships between these features both
developmentally and chemically. X-ray
diffraction is being used to compliment micromorphology results as to what
minerals are present in these soil horizons.
This study will provide a more extensive look into the genesis
of highly developed petrocalcic horizons.
Applications of this research can be applied to understanding other
similar soils throughout the world and regionally, results of this study will assist
in characterizing previously unstudied southern Nevada
soils and associated geomorphic surfaces associated with the Colorado