Portland State University Active Rock Glacier Inventory (PSUARGI). This GIS inventory, developed at Portland State University, identifies 10,332 active rock glaciers of the Contiguous United States. Each active rock glacier polygon is classified as a Class 1, Class 2 or Class 3 feature. Class 1 rock glaciers appear to be highly active, Class 2 rock glaciers appear to be intermediately active, Class 3 rock glaciers appear to be minimally active.