The Geologic History of Tamanowas Rock

Jeff Tepper, Chairman of the Geology Dept. at the University of Puget Sound in Tacoma, spoke about Tamanowas Rock, a sacred site for the Callam Tribe and local rock climbing site located just west of Chimacum.  This illustrated lecture was attended by about 120 geology fans. After the talk, Jeff and other geologists in the group led 105 Tamanowas enthusiasts on a 2-mile round-trip walk from the Tri-Community Center to the rock where its geology and sacred status will be discussed.

Tamanowas Rock is an atypical volcanic rock that was emplaced by an eruption about 44 million years ago.  This particular rock is an Adakite, which occurs when hot mantle rises through a gap in a subducting tectonic plate and causes the edges of the plate to melt.  Use the slider bar below to hear an interview with Jeff about Tamanowas Rock recorded as part of Phil Andrews Tossed Lettuce program on KPTZ,

To the left; Jamestown S’Klallam tribe member from Sequim, WA, performs a ceremony at the base of Tamanowas Rock

On the right:  Outcrop of adakite, which is the rock type that forms Tamanowas Rock.  Notice the adundant gas cavities which are typical of an adakite.