Just north of Hwy 2 between Cashmere and Dryden.
Peshastin Pinnacle is a thick sequence of inter-bedded sandstone, shale and conglomerate known as the Chumstick Formation. It is also the center attraction of Peshastin Pinnacles State Park some 14 miles NE from Wenatchee. The state park has been a favorite with rock climbers for many years. It is well known for its slabs, spires and rounded cracks. Several of its spires reach quite high into the air.
Geologist Brent Cunderla, Area Geologist with the USDI-Bureau of Land Management in Wenatchee describes the sandstone as “silicified” or cemented with silica cement. “That’s what makes the sandstone very resistant to weathering and great for climbing.”
The Chumstick Formation of shales, siltstones and sandstones formed about 42-51 million years ago. Faulting and folding events include folding and thrusting of the Wenatchee Formation, and faulting along the Leavenworth, Eagle Creek and Entiat faults and faulting throughout the deposition of the Chumstick Formation.
The depositional environment ranges from fluvial (stream) to lacustrine (lake). Most common are sandstone and conglomerate in massive beds. The Nahahum Canyon Member sedentary sequence contains much more siltstones (north of the Eagle Creek Fault). The Chumstick formation contains numerous volcanic ash (tuff) beds.
The Chelan Douglas (Counties) Land Trust fought hard to make the area public land. The site is now a geological wonder, a state park, photographic attraction and a pleasant picnic area. It is indeed unique.
Reference:
Brent Cunderla, area geologist, USDI Bureau of Land Management, Wenatchee E-mail to K-Ddid the following answers to qualify for a find:
To claim this EarthCache complete the following before listing your find:
1. What are the two main geological components of the pinnacle?
2. Approximately how high do some of the spires extend into the air?
3. What year did Pinnacle Rocks become a state park?
4. Submit a photo of you with your GPSr at the Pinnacles.
This cache was adopted over to Mr. Gadget #2. Your answers will be evaluated and IF THEY ARE NOT satisfactory or incorrect, I will be contacting you. Also some of the questions can not be answered as the information sign has been removed. Will have to wait until State Parks replace it.
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