Friday Field Foto #93: Permian debris flow deposit in Death Valley
This week’s Friday Field Foto is from the Death Valley region in California and shows a very nice debris flow deposit (note the hand in the lower right of photo for scale).
This is from the Permian section in a location called Darwin Canyon (I forgot the name of the formation).
This particular deposit at this location was nearly 10 meter thick and sandwiched in between turbidite successions many tens of meters thick stratigraphically above and below. This example exhibits some of the key criteria for recognizing a debris flow deposit:
- muddy matrix (in these rocks it has weathered to that light brownish color)
- clasts of variable size and shape “floating” in the matrix (i.e., matrix-supported conglomerate)
- lack of internal organization (i.e., no discernible trends like normal grading, for example)
- lack of sedimentary structures that indicate traction sedimentation (e.g., cross-bedding)