The Facey Rock area includes approximately 4 square miles in
the Eastern Paleozoic Subprovince of the Klamath Mountains north
of Callahan, California. The structurally complex terrain is composed
of sparcely fossiliferous Silurian graywacke, sparsely fossiliferous
Ordovician limestone, Devonian to Cretaceous chloritic
quartzite and minor gabbroic and dioritic intrusive rocks.
The two limestone lithologies recognized in the area are the
Late Ordovician Platy Limestone Member and the Middle Ordovician
Massive Limestone Member of the Facey Rock Limestone. These are
interpreted as shallow water carbonate bank and deeper water carbonate
deposits respectively. Both contain minor amounts of primary
bedded chert. The graywacke is interpreted as a proximal
turbidite. The chloritic quartzite is believed to be an upper plate
remnant of the Devonian to Cretaceous, regional Mallethead Thrust.
Several large, recent landslides are located in the vicinity of
Facey Rock. Portions of the landslide debris along with talus deposits
have been cemented into a loose breccia by groundwater supersaturated
with calcium carbonate.
Thrust faults separate the two limestone members from each
other and from the underlying graywacke. They are responsible for
the successively older, upward sequence of units observed at Facey
Rock. These thrusts are considered subsidiary to the regional Mallethead
Thrust. There are numerous high angle faults in the area postdating