My next post about the Geology of the National Parks Through Pictures is from our move across the country from Utah to New York. Along the way we visited 13 National Parks as well as some other sites. This was the 13th, and final, National Park along the way.
You can find more Geology of the National Parks Through Pictures as well as my Geological State Symbols Across America series at my website Dinojim.com.
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Obligatory entrance sign photo
Herbert Hoover is notably the only geologist (to date) to have become president. His wife, Lou, was also a geologist, and the first woman to receive a geology degree from Stanford University. And while you would hope that a geologist would have many geological tidbits around his National Historic Site, there are not many across the park.
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| Schoolhouse |
In front of the schoolhouse there is a sign that has a little geological tidbit about Hoover. It is assumed that Hoover attended school here from age 5 until ~10 or 11, after which he went to live in Oregon with his uncle after he was orphaned. Eventually, he attended Stanford and received a degree as a Geological Mining Engineer, with the photo in front of the school house here, showing Hoover as part of a geological survey squad in 1893.
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| Herbert Hoover Birthplace Cottage |
Another site within the park, the Birthplace cottage, has some geology to it. The foundation of the birthplace cottage had been changed over the years, with the original foundation having been constructed using local boulders found on the prairie. The cottage was then purchased by another family and moved in 1889. However, it was then restored to its original location in 1934, when the Hoover family repurchased it. The stones used for the current foundation is a "local stone", however I can't find any more information on the specific rocks used. My guess is that it is a dolomite (a type of limestone), because the park sits upon several dolomite formations.
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| Geological map of Herbert Hoover National Historic Site and surrounding area. Image courtesy of the NPS. |
The majority of the park sits upon the Silurian Age (~430 million years old) Scotch Grove Formation and the ~425 million year old (still Silurian) Gower Formation. Both of these are fossiliferous dolomites that formed in fairly shallow marine environments. These rocks are slightly younger than the bedrock below the nearby Effigy Mounds National Monument. If the stones for the birthplace cottage were quarried locally, it is likely that one of these two formations were the ones quarried.
One of the most notable geologically related construction stones are the marble slabs used for the grave markers for both President Hoover and his wife, Lou. The marble slabs are noted as "Vermont white marble", however there is little information besides this to identify the quarry, region, or formation of the marble use. It is assumed that, due to the time period that these slabs would have been quarried, and the importance of the memorial (being a former president) that these are likely from the Danby Imperial quarry.
The Danby quarry is the largest underground marble quarry in the world. This quarry, located in the northeast flank of Dorset Mountain in Vermont, mines the Columbian member of the Lower Ordovician Shelburne Formation (~480 million years ago). These marbles were originally deposited as a limestone within a shallow marine environment. Then burial under other rocks and metamorphism from mountain building heated the limestones up and folded them, altering the minerology to produce the marbles as they are today. Blocks of marble from this quarry have been used in the New York Public Library, the Jefferson Memorial, Harvard Medical School, the U.S. Senate Building, Arlington National Amphitheater, the Supreme Court, and the United Nations building.
Although it is possible to find some of the bedrock along local stream channels, the majority of the bedrock within the park is located fairly deeply beneath glacial sediments (hence the original boulders used for the birthplace foundation) that were deposited during the early and middle Pleistocene Epoch (about 2.6 million years ago to 500,000 years ago). These glacial deposits are known as the Pre-Illinoian Alburnett and Wolf Creek formations, which comprise mostly of till, a glacial deposit that is essentially a clay rich mishmash of everything that can be thrown into one pile. Think of a glacier scouring the surface of the earth and then just dumping everything it picks up into a pile like a conveyor belt. That is till.
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