A STUDY OF PATTERNED GROUND AT TRINCHERA PEAK, COLORADO

In 2000, relict patterned ground was discovered on Trinchera Peak (4120m), Culebra Range, Sangre de Cristo Mountains, southernmost Colorado. This preliminary study is an attempt at determining a minimum age of the patterned ground formation. Methods included photographing the site, recording measurements of Rhizocarpon geographicum lichens, collecting soil samples, and recording soil temperatures. Lichen measurements of the patterned ground were compared to a lichen growth rate created by Benedict (1967) from the Indian Peaks area in the Colorado Front Range. Lichen measurements taken in 2003 suggest a minimum age of patterned ground formation to be approximately 600 years before present. This is 76-136 years younger than Tilton (2003) had concluded doing similar lichenometry in 2001. Soil analyzed to a depth of 60 centimeters revealed an organic soil horizon had developed to a depth of 10 centimeters and another horizon had developed at a depth of 30 centimeters. The soil thickness and horizon development indicate an extensive period of soil formation and development. A temperature data logger was buried at a depth of 60 centimeters to record soil temperature every 6 hours. Soil temperature data was acquired from August 12, 2003 to June 23, 2004. During this period the average soil temperature was -3.4^oC. The lowest soil temperature of -10^oC was recorded from February 13th to February 19th and the highest soil temperature of 5.4^oC was recorded from August 12th to August 16th.