Erratic Art EarthCache
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Difficulty:
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Size: 
(large)
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This cache is located with the confines of Washington Park and is placed with permission. The park lies within the city of Anacortes and features camping, a boat launch, and day use picnic sites. A scenic 2.2-mile loop road winds through the park’s forested hills and meadows with views of the San Juan Islands and Olympic Mountains. The park is open year round from 6am to 10pm. The loop road is open from 6am to dusk for pedestrians and open from 10am to dusk for vehicular traffic.
The posted coords will take you to parking and the trail head. Follow it south until you see a sign that says, "To Burrows Channel Trail .14". I’ve also included waypoint coords for the observation areas to answer the questions.
Glaciers are the largest moving objects on earth. They are massive rivers of ice that form in areas where more snow falls each winter than melts each summer. Their scale is truly gargantuan!
The inexorable force of glaciers carves out lakes, grinds down mountains, scatters strange rock formations across the countryside and reduces solid rock to fine dust.
So how does ice carve out rock walls like the one located here? After all it’s just ice! If I took an ice cube from my freezer and rubbed it REALLY hard on my sidewalk, how much damage do you think it would do to the concrete? Ok, so the sidewalk wins. Glacial ice is basically the same stuff as the ice cube, so how can this wimpy material turn into a rock-wall grinding machine?
Well, what if I took a sharp rock and rubbed it REALLY hard against my sidewalk? How much damage to the concrete do you think I would do now? Yes, I would leave a scratch. Rocks that have been frozen to the base of the glacier get dragged along the ground, grinding the bedrock as they go like a giant piece of sandpaper.
This "glacial sandpaper" cuts grooves and scratches into the rock, as well as flattening and polishing one side of the rock. The "grit" of this glacial sandpaper, the rocks being dragged against the ground, also have grooves, polish and striations worn into them from contact with the bedrock surface, and even the "grit" grinding against each other (boulder against boulder). This process is called Glacial Abrasion and is just one of the two types of Glacial erosion. The other one is plucking. (See earthcache “Rock of Ages,GC3B756 for a geology lesson on that.) By mapping the direction of the flutes, researchers can determine the direction of the glacier's movement. Chatter marks are seen as lines of roughly crescent-shape depressions in the rock underlying a glacier, caused by the abrasion where a boulder in the ice catches and is then released repetitively as the glacier drags it over the underlying basal rock.
To qualify as a "find", email, (do not post online), the answers to the following questions. Please e-mail us at the same time you log your find. Failure to do that in a timely manner will result in a log deletion.
1) What does the sign say at the way point sign coords? Please do not take a picture of it!
2) What is the approximate height and width of the area that was impacted by the glacier here?
3) What appears to be the size of the rock that the glacier used to make this carving?
4) What direction did the glacier appear to take when it retreated from here?
If possible please post a picture of you or your GPSr with some of the views found in this park.
I hope you have learned a thing or two about the glacial impact on this area and thanks for visiting the Washington Park.
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