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Thunderbird Track #9- Glacial Rock EarthCache

1 out of 5
1 out of 5

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Geocache Description:

Thunderbirds – legend? Myth? Reality? Native tribes revered these giant birds and believed that they cause thunder by flapping their wings, while lightening flashes from their eyes. Legends have them both helping and attacking people. In 1992-3, Kitsap County placed 10 bronze tracks in strategic spots to tell the story of the water cycle. We have located 9 or the 10 tracks and have placed caches at all 10 sites. We hope that you will enjoy them as much as we do.

This track brings you to an island beach in a Kitsap County Park.Frozen water formed King County in much the same way that a construction crew builds a house. The crew brings in materials, adding some here, taking away some there, and then, when the job is finished, leaves.

So too with the frozen water that made up Ice Age Glaciers. The shape of the land and lakes, the makeup of the earth’s surface, the way the water flows beneath the ground, all were determined by the powerful forces of glaciers.


Imagine Puget Sound under a mile of ice. 20,000 years ago, glaciers covered everything in between the Olympics and the Cascade mountains and spread as far south as Olympia. The ice over Seattle was higher than five Space Needles (3,412 feet.) This huge glacier was called the Puget Lobe of the Cordilleran Ice Sheet.

Glacial ’erratics’ were also carried down; they are large boulders often seen along beaches or in open fields. Most were eroded from mountains in British Columbia, and fell on top of a glacier, whence they ‘hitchhiked’ down to the US as the glacier advanced. When the glacier melted, these boulders were left behind, a stone unlike any surrounding it now.

Glaciers containing up to 2,383 cubic miles of ice pushed over the Puget lowland. In some places, the heavy pressure of the ice sunk the earth's crust. When the ice finally retreated to the north, it left behind deeply gouged channels, north-and-south oriented passages and bays, creating ‘roller-coaster ‘ roads, up, down, up and down. As the glaciers moved north and south, they scooped out the land like a bulldozer, pushing it into ridges as they went. These, called Drumlins, occur all over Kitsap County, but the best ones here are in South Kitsap, and along Sedgewick Road.


Weather, waves, and gravity reworked the glacial sediment, molding landforms and shorelines like frosting on a cake. The results are the beaches and bluffs that now edge the Sound. Many shoreline bluffs reveal layers of glacial activity in soils and rocks. These layers can slide when saturated. The geology of Puget Sound bluffs varies from one location to the next. Although the generalized geologic conditions described here occur broadly and demonstrate common landslide-prone features, they do not apply to all shorelines and landslides are certainly not limited to these circumstances.

Please, in order to claim this virtual cache, email me with two answers: one- is this area made up of glacial till, outwash or silts and clays, and two- how many eyes on the track.

Congratulations to the Seabeck Tribe on FTF, in the rain!

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