Black Hills Highpoint EarthCache
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Harney Peak is located in the Black Elk Wilderness Area of the Black Hills. It is the state highpoint of South Dakota. Although there are several trails that will lead to the summit, the most popular one begins at Sylvan Lake in Custer State Park. Custer State park fees are $6/person or $15/vehicle. This is the shortest distance, a round trip journey of about 6 miles. No permit is required for use of the trail, although the National Forest Service requires that hikers register at a self-service kiosk along the trail upon entering the Black Elk Wilderness area, en route to the summit.
Please remember that all geologic features within the borders of the Black Elk Wilderness are protected by law, as are all natural and historic features. Please do not disturb, damage, or remove any rocks, plants, animals, or the Fire Lookout Tower.
Harney Peak, at 7,244 feet, is the tallest peak of the Black Hills, and the highest point in the United States east of the Rocky Mountains. A fire lookout tower is located on the summit. From the top, one can see into 4 different states. The Harney Peak Lookout Tower, Dam, Pumphouse, and Stairway are listed on the National Register of Historic Places.
The Harney Peak Granite are the youngest precambrian rocks in the Black Hills, estimated at 1.74 billion years old. The exposed granite is assumed to be the top of a much larger body extending to great depths.
The Harney Peak Granite is made up of several large and small intrusions and the texture and mineralogy show a lot of variability. The rock texture ranges from fine grained to coarse grained.
Granite is classified by 4 different types. I-type,S-type,M-type, and A-type.
I-type granite originated from igneous sources. Mica is not common in I-type granite.
S-type granite originated from sedimentary sources. Mica is common in S-Type granite.
M-type granite is derived from melting subducted crust or mantle.
A-type granite departs from the other types and is based on chemical characteristics. It is uncommon.
To log this EarthCache, send me an email with the answers to these questions:
1.) What is the grain texture of the granite at this location?
2.) Is this I-type or S-type granite and why?
3.) How many pieces of lumber make up the deck of the fire lookout in the tower?
4.) (optional) Post any pictures you like from the top or along the trail. This option can replace 1 of the first 3 questions.
Be sure to log the nearby benchmarks as well!
I will delete all unverified logs after a week goes by and the answers to the questions have not been emailed to me! Just posting a picture with your log does not meet the requirements of this cache!
The above information was compiled from the following sources:
Wikipedia. Harney Peak. (visit link)
Wikipedia. Granite. (visit link)
South Dakota State Parks, Custer State Park: (visit link)
Peakbagger.com. Harney Peak. (visit link)
Black Hills National Forest (visit link) Hills National Forest- Home
Geology of the Harney Peak Granite, Black Hills, South Dakota, by Jack A Redden. (1985)
National Register of Historic Places (visit link)
The US Forest Service, administrators of The Black Elk Wilderness was most helpful in the background discussion, aid in the choosing of sites, and review of this EarthCache. Please remember that this is a wilderness area and placing physical geocaches nearby is not allowed. Wilderness regulations can be found at the Black Hills National Forest Website.
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