Morphology and Pattern of Earth Mounds in South-Central Colorado

Abstract

Earth mounds in south-central Colorado occur in discrete clusters from 2377 m in the San Luis Valley to 3841 m on an alpine ridge in the Sangre de Cristo Mountains. Discriminant analysis and analysis of variance demonstrates that size and spatial relationships occur between the earth mounds in the different environments of this region. The height of an earth mound increases with altitude and distances between mounds correspondingly decrease. The largest earth mounds are located in the highest field; however, length and width values do not change systematically with elevation. The shape of the earth mounds, slightly longer than wide, is not significantly different between areas although the average slope of the sites studied varies from 1.6 to 10.4°. Using a modified nearest neighbor analysis, the discrete pattern or arrangement of earth mounds is identified as being more regular than random. Regularity of pattern and uniformity in nearest neighbor distances are detected even though the size of earth mounds vary at a site. The results of discriminant analysis, analysis of variance, and nearest neighbor analysis indicate that the earth mounds of south-central Colorado are part of one population of landforms rather than being different landforms as visual contrasts might suggest.