MURPHREE'S VALLEY; GEOLOGICAL FORMATIONS. 27 



called, is the Sparry Limestone. This member is wholly 

 composed of limestone, with occasional thin beds of soft 

 shale. The limestone is generally blue, and crossed with 

 seams of Calcite or lime spar in all directions. It is a rock 

 that has been noted and studied in many parts of North 

 America. In the Canadian Survey it is called the "Levis 

 Limestone ;" by others the "Sparry Lime rock." Saiford, in 

 his Geological Survey of Tennessee, grouped it with under- 

 lying and overlying members, and called it "Knox Shale. 

 More recently, however, the United States Geological Survey 

 has definitely placed this rock in the scale as Upper Cam- 

 brian. And Prof. Walcott, Chief Paleontologist of the Sur- 

 vey, who has given much labor to the study of its fossils, 

 draws the line between the Upper Cambrian and the Ordo- 

 vician or Silurian, at the top of this rock, or rather between 

 this rock and the clearly defined Silurian strata above, thus 



ilar thin-bedded limestones with clay seams or bands immediately belo-v 

 strata of undoubted Knox Dolomite age. These shaly limestones underly 

 usually level tracts of badly drained lands, to which the name "Flatwoods" 

 has been given. 



In consideration of the facts above named we were led, in the Preface to 

 the Plateau Report, published in 1891, to the conclusion that the lithological 

 variations in the Cambrian strata of Alabama were due, in the main, to 

 geographic position; that while sandstones and sandy calcareous shales were 

 accumulating along the eastern border of the Coosa Valley area, limestones, 

 and alternations of limestone with clay beds, were accumulating further 

 westward, presumably more distant from the coast line of that period; and 

 that the "Flatwoods" limestones, with their inter-bedded clay seams, are 

 the time equivalents, not only of the Coosa Shales, but also of the Chocco- 

 locco or Montevallo Shales and their included sandstones. 



To sum up, the Cambrian of Alabama consists of thin-bedded limestones 

 often with clay partings (our Coosa Shale or Flatwoods rock), passing 

 downward into siliceous limestones and calcareous shales, which, towards 

 the east, graduate into calcareous sandstones, alternating with calcareous 

 shales (Choccolocco or Montevallo Shales), and enclosing, near the base of 

 the series, great beds of sandstone, often conglomerate. The type of these 

 sandstone masses is the Weisner Sandstone of Cherokee county, which is, 

 I think, undoubtedly the equivalent of Dr. Safibrd's Chilhowee. These 

 sandstone masses and the beds of calcareous sandstone near the base of the 

 Cambrian seem to be confined to the eastern border of the Coosa Valley, 

 while further westward in Wills', Murphree's, Opossum and Jones' Valleys 

 the limestones with clay seams or partings are the only Cambrian rocks 

 exposed. E. A. S. 



