GPR survey of a lobate rock glacier in Yankee Boy Basin, Colorado, USA Academic Article uri icon


  • The internal structure of a lobate rock glacier located in the San Juan Mountains of southwest Colorado was investigated using ground penetrating radar (GPR). A 440 m, 25 MHz longitudinal profile oriented along the central axis of the rock glacier shows moderate to strongly coherent reflection horizons or layers that can be recognized clearly to a depth of 30-35 m. The layers are interpreted as representing ice-supersaturated sediments and coarse, blocky rockslide debris that are the result of flow, perhaps generated by seasonal snow pack covered by episodic debris flows or high-magnitude discharges of talus from the cirque headwall. Profiles collected at 50 MHz indicate that, in the upper 20 m thickness of the rock glacier, many of these layers are laterally continuous. The total depth of penetration (-40 m at 25 MHz) was sufficient to detect the rock glacier-cirque-floor contact, which is composed of underlying moraine. Several prominent reflection events that subdivide the profile into broad 10-15 m-thick layers represent contacts between major depositional units. These units are believed to be individual flow lobes that were initiated at various cirque-headwall locations. We interpret this rock glacier to be a composite feature that formed by a process involving the development and subsequent overlap of discrete flow lobes that have over-ridden older glacial moraine and protalus rampart materials. The latter materials have been incorporated into the present flow structure of the rock glacier.

published proceedings

  • Geological Society London Special Publications

author list (cited authors)

  • Degenhardt, J. J., Giardino, J. R., & Junck, M. B.

citation count

  • 21

complete list of authors

  • Degenhardt, John J||Giardino, John R||Junck, M Brian

publication date

  • January 2003