Named as lower member (of 2) of Echooka Formation of Sadlerochit Group for exposures near Joe Creek, tributary of Firth River. Type section designated along south slope of mountain north of Joe Creek, 18.5 km (11.5 mi) N 68 deg W from point where Joe Creek crosses Canadian boundary, 68 deg 59'30"N, 141 deg 26'W, northern part of Table Mountain quad, northeastern AK. Also exposed in mountains along southern edge of Demarcation Point quad and in many sections along north front of Brooks Range. At type consists of (ascending): dusky-yellow limy mudstone and calcareous siltstone (about 200 ft thick), chert and siliceous siltstone (about 90 ft thick), and calcarenite and bioclastic limestone. Total thickness is 372 ft at type. Transgressive onto underlying Wahoo Limestone of Lisburne Group. Conformably underlies Ikiakpaurak Member (new) of Echooka Formation. Age ranges from Wolfcampian (early Sakmarian) to Guadalupian (early Kazanian) based on brachiopod fauna. [Thus age is Early and Late Permian].

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