Periglacial rock glaciers are fields of talus sourced from adjacent highlands that are formed from periglacial processes. The combination of intense freezing (frost) and the melting of snow cause the core of the rock glacier to develop ice as talus accumulates on top. Both types of rock glaciers appear physically the same. The main way to differentiate between the two is to examine the glacial history of the region or to map periglacial features to determine the extent (if any) of Pleistocene glaciation.
There are two distinct physical types of rock glaciers; tongue-shaped and lobate. Tongue-shaped rock glaciers possess a greater length than width and are normally confined to narrow valleys or cirques. Talus is derived from steep and rocky highlands proximal to the head of the glacier. Lobate rock glaciers have a greater width than length. The talus source is derived from adjacent valley walls that enclose or encircle the lobate rock glacier. The talus contributes to a lobate rock glacier’s growth from multiple sides whereas the talus only contributes to the growth at the head of a tongue-shaped rock glacier.