87h033: Falls of the Ohio : 無料・フリー素材/写真
87h033: Falls of the Ohio / Bill Alden
| ライセンス | クリエイティブ・コモンズ 表示-継承 2.1 |
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| 説明 | Looking SE from Falls of the Ohio.Shallow pool near McAlpine Dam (at right).Conrail (later L&I) Bridge in distance.Seen here is the limestone bedrock which forms the Falls of the Ohio. [Some of the rock in this photo is in the form of slabs which may have been dumped here during dam construction.] The coralline zone is the lowest layer of the Jeffersonville Limestone (named for the nearby city), which in this area is about 25 to 35 feet thick, depending on where it is measured. The coralline zone is about 8 to 11 feet thick and is named for the many species of fossil coral found in it. This limestone dates back to the middle Devonian Period, about 375 million years ago, when the continental plates were arranged much differently than today. The Falls area at that time was nearer to the equator, the bed of a shallow tropical sea, somewhat like the Bahamas today. Many of the animals in the sea had calcium carbonate shells or skeletons which settled to the bottom when they died. Together with the waste products of living animals, the remains formed a sediment which over time lithified into limestone. Much later in geological time, during the last 10,000 years, the Ohio River eroded down through glacial deposits until it reached the limestone bedrock seen at the Falls. Before the dam was built, the bedrock was exposed at low water across the entire width of the Ohio River, forming rapids about 2 miles long with a drop of about 26 feet. These rapids, known as the Falls of the Ohio, were a natural barrier to navigation and stimulated the early development of Louisville, Jeffersonville, Clarksville and New Albany.See also:Falls of the Ohio Educator's Handbook (PDF).Fossil Beds of the Falls of the Ohio (PDF).Powell, Richard L., 1970 (revised 1999). Geology of the Falls of the Ohio River: Indiana Geological Survey Circular 10.Conkin, James E., and Conkin, Barbara M., 1980. Handbook of Strata and Fossils at the Falls of the Ohio: University of Louisville Studies in Paleontology and Stratigraphy.Ohio River mile 605.Kentucky owns the river, but the Falls are accessible from Clarksville, Indiana.Aug. 1987.File # 87h033..35 mm E-6 slide.scanned with Plustek OpticFilm 7600i and Silverfast 8.edited with Picture Window 4 |
| 撮影日 | 1987-08-01 00:00:00 |
| 撮影者 | Bill Alden , Louisville, Kentucky, USA |
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| 撮影地 | Louisville, Kentucky, United States 地図 |