Named for Mount Morrison where formation crops out on summit and east flank. Type locality designated as easily accessible low ridges immediately west of Convict Lake, Mount Morrison 15' quad, Mono Co, CA. Discontinuously exposed along strike for 5 mi from its northernmost exposure 1.5 mi northwest of Convict Lake, southeast to its termination against granodiorite .5 mi northeast of Mount Baldwin. Shown on geologic map as part of Convict Lake block. Consists chiefly of fine to medium-grained calcareous quartz sandstone that ranges in color from white to medium-dark gray with lighter shades predominate. Generally sandstone is very thick-bedded or massive, although locally it is laminated. Ranges in thickness from about 1000 ft northwest of Convict Lake to about 1800 ft near south end of moraine-filled cirque south of Convict Lake. Conformable with underlying Convict Lake formation (new); contact generally sharp or gradational over few ft. Underlies sandstone or hornfels of Sevehah Cliff (informal group). Is Ordovician or Silurian(?) age on basis of stratigraphic relations.

Source: GNU records (USGS DDS-6; Menlo GNULEX).