Boulder Junction EarthCache
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This is not your typical geocache; it is an EarthCache. Instead of looking for a "cache container" you will be brought to a geological feature.
ABOUT THIS LOCATION: This EarthCache is on the Ice Age Trail just off of Highway 33. Parking available in the shopping parking lot. The posted coords will bring you to a geological sign.
GEOLOGICAL INFORMATION:
A glacial erratic is a piece of rock that differs from the size and type of rock native to the area in which it rests. "Erratics" take their name from the latin word "errere", and are carried by glacial ice, often over distances of hundreds of kilometers. Erratics can range in size from pebbles to large boulders.
At the listed coordinates, you will see an Ice Age trailhead sign and a geological sign describing how an erratic arrived here. Information on the sign is provided by iceagetrail.org.
The bedrock here, which is under thick glacial deposits, is Silurian age (443-417 million years ago) sedimentary rock called dolomite.
While Moraines are made up of small rocks and gravel ground up and pulverized under the weight of the glacier, erratics remain as large rocks because they traveled on top of the glacier. The glacier brought them down from the north like a huge but extremely slow conveyor belt. When the glacier melted, the erratics were left on top of the morainal material.
Geologists identify erratics by studying the rocks surrounding the position of the erratic and the composition of the erratic itself. Erratics are significant because; Since they are transported by glaciers, they are one of a series of indicators which mark the path of prehistoric glacier movement. Their lithographic origin can be traced to the parent bedrock, allowing for confirmation of the ice flow route.
EARTHCACHE INFORMATION: Bring a compass. To receive credit for this EarthCache please complete the following six requirements (enclosed text and posted geological sign will help you):
1) Erratics take their name from the latin word______________.
2) Erratics remain as large rocks because they traveled on ________of the glacier.
3) Some of these erratics were transported here from as far away as ___________.
4) Describe each of the three erratics lying closest to the geological marker at ground zero with respect to their color, texture, and shape.
5) Do you believe that the three erratics found here where all picked up at the same origin by the glacier? ______. Why or Why not? ___________________________________________________________________.
6) Using your compass, what bearing (using degrees) are each of the three erratics from the geological sign?
You do NOT have to wait for confirmation from me before logging your find. Please do not make any reference to these answers in your log.
Please be advised, failure to complete the six tasks listed above will result in log deletion without notice.
DNR forms sent in January 13th to Terry Jensen.
I have earned GSA's highest level: Platinum EC Master
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