Sketch of the Geology of Alabama |
Other editions - View all
Common terms and phrases
abundant Alabama river angular anticlinal valleys Archæan bama belt black shale Blocton Blount Springs Bluff border brown iron Cahaba Cahaba coal field calcareous Cambrian Carboniferous Chattahoochee river chert Choccolocco clays Clinton coal measures Coosa county Coosa shales Coosa valley Creek Cretaceous Cretaceous and Tertiary crystalline rocks Devonian drainage level eastern eastward feet in thickness ferruginous fossils geological geologists Georgia line Grand Gulf horizon Jones valley Knox dolomite Lafayette land lime limestone localities lower marls materials McCalley mica miles mined mineral Miocene Mississippi Montevallo Montevallo shales occupied occur older Oxmoor Ozark sands Paleozoic Paleozoic rocks Pascagoula pebbles phosphate pyrite quarried quartz quartzite recently red loam Red mountain ridges rotten limestone Safford sandstones sandy schist seams second bottom deposits sediments shells siliceous siliceous matter Silurian soils strata streams surface Tallapoosa terrace Tombigbee river Trenton limestone Tuskaloosa upper usually Warrior field Weisner quartzite
Popular passages
Page 16 - Tennessee river we find it impossible to carry out this two-fold division of the lower or Siliceous member of the Sub-Carboniferous, for the entire member shows, upon the surface at least, little else than chert, which appears in a mantle of angular fragments, covering usually one side of all our Red Mountain ridges, a We have called this the Fort Payne Chert, and it is probably the representative of both the subdivisions of the lower Sub-Carboniferous or Siliceous group, of North Alabama and Tennessee,...
Page 27 - Tertiary have been given fully in the table (p. 388) at the head of the present article. A few words of explanation may be added: At the base of the Tertiary is found an impure limestone, thin and inconspicuous in west Alabama, but thickening eastward until, on the Chattahoochee river, it is fully 200 feet. "This we have called the Clayton limestone, formerly known as our Midway group, from a locality on the Alabama River.
Page 12 - ... one. The Knox Dolomite as well as the upper part of the underlying formation seems to have held originally much ferruginous as well as siliceous matter, and we find throughout the region formed both by the Dolomite and the upper part of the Shale, beds of the brown iron ore or limonite, which plays so important a part in the economic history of all this region. The iron ore seems to have been derived from these older rocks. As instances of the occurrence of limonite banks connected with the Dolomite...
Page 8 - ... put at 10,000 feet; but this great thickness is seen only in the eastern part of the Coosa valley.
Page 11 - ... ridges of the Knox Dolomite. In the region covered by this map, we have found it convenient to distinguish the area underlaid by the lower and more calcareous part of the formation and that formed by the upper or more siliceous part. In the former, the weathering of the limestones and dolomites has given rise to the formation of gently undulating terranes with a deep red-colored sandy loam soil of more than average fertility, which is the base of the best farming lands in all these valleys. The...
Page 12 - Safford was the first to call attention to this mark, which we have found to be an extremely useful one. The Knox Dolomite as well as the upper part of the underlying formation seems to have held originally much ferruginous as well as siliceous matter, and we find throughout the region formed both by the Dolomite and the upper part of the Shale, beds of the brown iron ore or limonite, which plays so important a part in the economic history of all this region.
Page 12 - ... of fragments of the Knox Dolomite, is of course younger, though on account of its materials we have usually classed it along with the Knox Dolomite. It is seen in greatest volume in the Salem Hills southwest of Bessemer, but occurs upon the Flint ridge forming the North Highlands at many pionts, eg Birmingham and Gate City, and also west of Springville. It has been called the Birmingham breccia by Mr. Russell of the United States Survey, and Salem breccia by us in the State Survey. It is of interest...
Page 12 - The iron ore seems to have been derived from these older rocks. As instances of the occurrence of limonite banks connected with the dolomite and shale, I may mention the Edwards ore bank, near Woodstock, the mines at Greely and Goethite, in Jones valley, and the great beds at Shelby, over the Coosa. The great bulk of the brown iron ores of Alabama is from this horizon. At the top of the Knox dolomite, and belonging perhaps to the next succeeding division, there is rather a peculiar rock occurring...
Page 15 - ... chiefly* perhaps, as being the source of some of our best known sulphur springs. The shale usually contains a large amount of pyrite in the form of nodules or kidney-shaped concretions, the decomposition of which supplies the sulphur of these springs. In North Alabama the thickness of the Black Shale may go up as high as 100 feet, but so extreme a thickness is rarely seen further south. THE CARBONIFEROUS.— This we conveniently divide in Alabama into two parts, a lower, or Sub- Carboniferous,...
Page 15 - Barrens" ; the upper part of the Siliceous member is more calcareous and the soil derived from its disintegration is a red loam of more than ordinary fertility, well known in the Tennessee Valley as making the best farming lands of that section.