VA - McCormick's Rocks Earthcache EarthCache
VA - McCormick's Rocks Earthcache
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Difficulty:
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Terrain:
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Size: 
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As an earthcache, there is no “box” or “container” to discover. Rather, with this cache, you discover something about the geology of the area. For more info, consult www.earthcache.org
The McCormick Farm is only a few miles from the interstate and offers a wonderful rest stop for travelers. There is a grist mill and small museum that displays several of McCormick's farming innovations/inventions. Please see "history" below for a more complete historical description.
YOU WILL NEED A "HARDNESS TOOLKIT." PLEASE BRING YOUR TOOLS WITH YOU!
For paperless cachers, the logging requirements have been listed first to avoid possible truncation.
Logging Requirements:
Send the answers to #1-#4 to me through my geocaching profile. DO NOT post the answers to any logging requirements on this site.
1.List the name “GC2GJ2N McCormick's Rocks Earthcache” in the first line of your email. Also, list the number of people in your group.
2.Which do you think is harder – the grinding stones used at the mill or the rocks that are breaking out of the soil all around the earthcaching location?
3.Test the hardness of one of the native boulders at/near the posted cords. Use the common test tools outlined below.
4. determine whether the limestone/dolomite present was likely laid down during the first/second bank (no sand interspersed) or during the third bank (sand interspersed, see below).
5. (optional of course based on the new Geocaching.com guidelines, though of course a picture helps verify your find if some of your other logging answers are "less than accurate.") Post a picture of yourself and/or your GPS with your log that shows one of the grinding wheels present at the mill.
I will only respond if you have incomplete logging requirements. Go ahead and log your cache
Getting There:
You will be able to walk the grounds of the McCormick Farm and examine the examples of farm machinery that historically trace the development of the McCormick reapers. Enjoy the time! As a child I always enjoyed stopping here on my way to my grandparent's house, since the mill wheel was often running and the grass provided an open place to run.
Hardness Test:
Progressively work from lowest to highest number items until something SCRATCHES the rock.
Fingernail – 2.5
Penny – 3.0
Butter knife / pocket knife blade – 5.5
Penny nail – 6.3-6.5
Geology: There are two types of rock present in the area, one naturally and one brought by man to assist in the milling process. Both are "laying around" on the ground at the McCormick farm.
First, there are sedimentary carbonate rocks (limestone and dolomite). When they are metamorphized, they both become Marble. There are several places in Virginia where this has happened, but not here. In their "non-metamorphed" form, limestone and dolomite are hard to tell apart! However, if you had a some chemical tests, you would be able to tell whether the carbonate rock present here, since magnesium is present ONLY in dolomite. Cement companies are very aware of the difference that magnesium, since concrete will NOT form if magnesium is present. Thus, only limestone is "eligible" to be used for cement!
In the Valley & Ridge province of Virginia (west of the Blue Ridge), dolomite tends to be in the rock formations in the western regions, while limestone tends to be present in the eastern parts of the province.
"Three separate carbonate banks are preserved in the rock bank of Virginia: of early, middle, and late Paleozoic age. Al three contain both limestone and dolomite." (Roadside Geology of Virginia, 1984).
The first bank was the largest and was laid down from early Cambrian to mid-Ordovician times. This bank spread form Texas to Virginia. The second bank was laid down from the upper Silurian to the lower Devonian times. The third bank was only laid down in western Virginia and was laid down during a relatively brief period of time during the late Paleozoic era. This last bank has sand and gravel interspersed with the limestone and dolomite, making for a very jumbled geological display!
The carbonate banks in the area were created in a shallow sea. Each of the seas ended when mountains were created and shut off water supplies. Because there is little clay and sand (especially in the first two banks), it is believed that the shallow seas were VERY stable and didn't rise and fall very much (or they would have eroded the hillsides and put sand and clay in the mix). However, when mountains rose and deeper oceans replaced the warm seas, the banks were no longer deposited!
Secondly, igenous rocks -- shaped and used for milling grain/corn.
Milling rocks are always composed of igneous rocks, usually basalt though sometimes granite. You can identify which one it is by seeing if you can identify any "crystals" on the grinding rock. If you can, that granite. If not (or the crystals are VERY small, then it is granite...sure I know there are more specifics, but that is sufficient for this geology lesson!
Milling rocks, composed of igneous rocks often lasted for years, grinding thousands of baskets of raw wheat and corn for area farmers. The reason is that igneous rocks were created by intense heat (volcanoes and the like) and were solidified as the magma neared/reached the surface. The cooling time was sometimes rapid (basalt) and sometimes slow (granite), but either way, a weathering-resistant rock was formed.
History:
(Available online and from visitor panels within the structures -- "Robert McCormick moved from Cumberland County, Pennsylvania in 1779 with his wife, Martha and their five children. He bought a log house and 182 ha (450 ac) on the Rockbridge and Augusta County line. He called his farm Walnut Grove. The farm and the McCormick name became famous when on a July day in 1831 Robert’s then 22-year-old son, Cyrus demonstrated the world’s first successful mechanical reaper. This important invention mechanized agriculture and made it possible for millions of people to leave the land and change theface of society worldwide.
Although Walnut Grove is best known as the location of the invention of the first successful mechanical reaper, it supported other enterprises besides production agriculture. Most notably was the operation of a gristmill on the farm.
The gristmill was built at Walnut Grove around 1800. The mill was operated until the late 1800's when it was phased out of operation. The McCormick family undertook a renovation of the mill in the 1930's. Local craftsmen were employed to restore the mill to its original condition. The mill was operated briefly and then allowed to become a static example of an early gristmill.
The McCormick family deeded their farm to Virginia Tech in 1954, and is now part of the Shenandoah Valley Agricultural Research and Extension Center. The mill underwent periodic repairs over the years to include replacing the wooden waterwheel axle with a metal axle in 1950's, replacing the shingle roof in 1993 and rebuilding the waterwheel in 1985. The waterwheel rebuilding was partially funded by a grant from the Society for the Preservation of Old Mills. Extensive rehabilitation and stabilization of the mill, dam and race were completed Spring 1997. A McCormick descendent, Mr. Hugh Trumbull Adams funded these improvements. As a result of this restoration, the mill is once again operational as it was in the 1800s." (scholar.lib.vt.edu)
Resources:
Frye, Keith. Roadside Geology of Virginia. Mountain Press. 1986.
Wikipedia Granite: (visit link)
(visit link)
Additional Hints
(Decrypt)
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