Prione

Rock, from the geologic map

Colluvium — colluvium. Quaternary, younger than 781,000 years.

Non-sorted deposits that consist of clay, silt, sand, and clasts that range in size from granules to large boulders, formed by a variety of mass-movement processes. Unit Qc chiefly includes small deposits in and near the foothills hogback belt and on slopes in montane areas, as well as extensive areas of block-slope deposits near and above present day treeline at about 3,475 m where freeze-thaw action has promoted mass-movement and downslope transport. The composition of the deposits reflect that of the bedrock or sediment from which the colluvium was derived. Unit Qc includes material transported by frost creep, solifluction, nivation and other periglacial processes, sheetwash, landslide, debris flow, hyperconcentrated flow, and rock fall. Unit Qc locally includes small bodies of undifferentiated valley-floor alluvium (Qa), mountain-valley alluvium (Qva), pediment deposits (Qp), sheetwash alluvium (Qsw), landslide deposits (Qls), and talus deposits (Qta). Estimated thickness is 3–15 m

This is the map unit under this crag's map point, read from the 1:100,000 sheet (Workman and others, 2018, U.S. Geological Survey Scientific Investigations Map 3399). The point can be a few hundred metres from the rock, a cliff often stands on the line between two units, and at that scale a line on the map is about 100 m wide on the ground, so the wall itself may be the neighbouring unit. The rock named at the top of this page comes from the public geology of this area; this card is the map's answer. Every crag on this unit: Colluvium. Geology data: Macrostrat (CC BY 4.0), serving USGS and Colorado Geological Survey maps.