Lyre Formation (Redefinition), Northern Olympic Peninsula, Washington

Abstract

Detailed geologic mapping in the northern Olympic Peninsula, Washington, has shown that conglomerate, sandstone, and siltstone strata, previously referred to the Lyre formation, are divisible into two mappable units. The Lyre formation, therefore, is redefined to include only a sequence of sandstone and conglomerate that comprised the lower part of the formation as previously described. These strata average about 1,300 feet in thickness but locally they may be as thick as 3,300 feet. Heretofore these rocks were thought to be Oligocene in age; however, recent field work indicates that they are early late Eocene in age and are overlain with erosional unconformity by strata containing Foraminifera of late Eocene age.