Vermilion Batholith and Other Earthly Delights-EC EarthCache
Vermilion Batholith and Other Earthly Delights-EC
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FAILURE TO EMAIL ME THE ANSWER AT THE TIME YOU LOG THE CACHE WILL RESULT IN YOUR LOG BEING DELETED..I WILL DELETE ANY SPOILERS (LOGS/PICTURES) THAT INDICATE WHERE THE CACHE IS LOCATED. Road cut on Co.Rd. 116 (Echo Trail), 19 miles north of Ely, Minnesota. Bring binoculars for the osprey nest sighting. NOT PLOWED OUT IN WINTER.
The purpose of this geocache is to give the cacher several unique experiences in one spot – geological, historical, and ornithological. GEOLOGICAL Geological 1. DEFINITION: BATHOLITH- A great mass of magma (molten rock) which is moved upward through existing rocks, solidifying as it rises toward the surface. Many times the batholith is 6-9 miles deep. By geographic definition it must cover an area of at least 40 square miles. The massive outcropping that you are looking at across the road from the given coordinates is an example of what is called the VERMILION BATHOLITH. This batholith extends over much of this area and north into Canada. What makes this site a geological interest is that the recent road excavation and blasting has exposed fresh rock surfaces. This is most important because the surface has not had time to undergo weathering, which will change the appearance of the minerals. You are basically looking at the rock like it was 2.7 billion years ago when it was formed. The intrusive igneous rocks of the Vermilion Batholith were formed below the earth’s surface by magma that was forced (intruded) into pre-existing rocks of the earth’s crust. The texture of igneous rocks is largely determined by the speed of which the melted matter is cooled, and the cooling is determined by the depth and volume of the magma. Magmas that intrude the earth’s crust at a depth of a mile or more cool very slowly and the mineral crystals have a long time to form. If such rocks are light in color, granular, and have a course grain, the rock is most likely granite. The most typical intrusive igneous rock found in Minnesota is granite. The Minnesota granites are among the oldest rocks on the surface of the earth. Granite’s are intrusive rocks, relatively coarse grained composed mainly of quartz and feldspar with hornblende and mica. The crystals formed deep and slowly, are large enough to be seen with the naked eye. The color of granite is always light varying from light and dark gray to pink and red. Pink granite contains pink feldspar and the gray granites contain the white/gray feldspar allowing the dark minerals to be seen easily. The most extensive granite outcrops like the one you see before you occur in NE Minnesota, but it is not often that you get to see them raw and exposed as they were when they first formed. (Adapted from Minnesota Rocks and Waters pp71-72 by Schwartz and Thiel). Geological 2. DRILL COLUMNS: You can still see many fresh vertical drill columns from the blasting. When a rock needs to be removed, the rock is drilled and explosives are placed in the holes. A charge is set off and the rock is fractured, and then removed to clear the way for construction. Geological 3. THE BENCH MARK. The cords given for this cache should take you to the bench mark where you can view the road cut across the Echo Trail which exposes the batholith rock. Many cachers also log benchmarks in a separate category of geocaching. Link: http://www.geocaching.com/mark/ HISTORICAL DUPONT HILL – the original hill in this area was known as DUPONT HILL. The reason for this being that the DuPont Company considered this granite, “pure.” The Vermilion granite density was 165 lb per cu. ft. and they considered this the most viable rock to test the quality of their explosives to make sure they worked correctly before being used in the local iron ore mines by the miners to extract the ore from the mine veins. THE LAKE. The lake opposite the exposed batholith is named ED SHAVE LAKE. Who was Ed Shave, you might ask? This lake at one time was called SECOND LAKE – on the way up the Echo Trail you saw the sign for First Lake. Ed Shave was a writer, in the 1950’s for the Minneapolis Tribune newspaper, who wrote many articles about the area around the city of Ely, Minnesota – extolling its virtues as a vacation destination. In his honor, for what he did for the Ely area, they renamed the lake after him – ED SHAVE LAKE. The official name change ceremony was held on Sept.22,1957. Here is a link to the lake features: http://www.fishingworks.com/lakes/minnesota/st.-louis/angleworm-lake/ed-shave-lake/ ORNITHOLOGICAL THE OSPREY NEST. Facing the lake from the benchmark, on the far shore to the left there is a tall white pine with a flat top containing an osprey nest. Depending on the time of year,with binoculars, you may be able to see the fledgling ospreys. The nest has been here for many years. Link: http://en.wikipedia.org/wiki/Osprey TO GET CREDIT FOR THIS CACHE EMAIL ME THE ANSWSERS TO THE FOLLOWING: No credit for cache without the two answers correct. 1. Send me the estimated height of the outcrop above the road surface at the highest point across from the benchmark. 2. Standing at the benchmark, what are the two predominant colors of the granite in the rock cut?
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