A fossil marmot from New Mexico and its climatic significance

Abstract

Fossil marmot bones found at an altitude of 5900 ft. on New La Bajada Hill, New Mexico, belong to a species now living near and above timber-line in the Sangre de Cristo Mts. A lowering of life zones of 4000 ft. at some time in the past is necessary to explain the presence of this fossil marmot. This lowering of life zones presumably occurred during the late Wisconsin. So large a depression is difficult to reconcile with previous estimates of the magnitude of climatic changes in this area during the Wisconsin. However, it is corroborated to some extent by finds of fossil marmots at other localities. Ancient landslides, now inactive, at several localities in the Southwest have been attributed to a period of greater humidity and intensified frost action. Similar inactive landslides occur at New La Bajada Hill. The inference that they, too, were formed under climatic conditions now existing only at higher altitudes receives support from this find of marmot bones in dust-filled cracks formed when the landsliding was active.