SUBTERRANEAN VS SUBAERIAL FORMATION OF FLARED SLOPES ON GRANITE TERRAIN VEDAUWOO STATE PARK, WY

Granitic erosional residuals known as pedestal or mushroom rocks occurring in Vedauwoo State Park, Medicine Bow National Forest, WY, posses a wide variety of atypical flare orientations. Conflicting arguments continue today as to whether these formations are produced from subaerial and/or subterranean mechanisms. Intense climatic variations on the Sherman granite erosion surface have a large influence on the weathering front of the granite. Locating these pedestals with GPS (hand) measurements, measuring their profiles, and methodical photographic documentation were the primary field methods used in this study. Logging the features on topographic maps and Google Earth^TM has shown no preferential geographic locality or flare orientation in the direct study area. Excavation by hand was done on one particular feature to examine the depth of bedrock near a sample as well as to expose any additional potential subterranean basal flares. The upper bulbous cap of the pedestals tended to be darker in color and covered in various lichens. The supportive columns, however, were significantly lighter in color suggesting faster weathering rates than the cap above. Accumulation of moisture containing salts in the surrounding regolith can produce extreme chemical weathering in and around the pedestals. Continuous exposure to moisture can therefore enhance the subterranean rotting of biotite into clays, weakening the rock into residual feldspar and quartz clasts (grus). Old plain surfaces originally located at widest points of the upper caps have progressively lowered over time from water and wind erosion. Continuous erosive events exposing columnar basal flares suggest possible polygenetic formation.