Geology. 



133 



sandstones, shales, and calcareous strata, but containing throughout more 

 or less magnesian limestone. 



It consists of three members, or subordinate groups, as follows : 



1. The Sandstone Member. — This — the lowest sub-group, many hundred 

 feet in thickness — is made up mostly of brownish-red, sometimes pale 

 greenish, smooth fine thin sandstones, abounding in fucoidal remains, 

 and occasionally approaching slate in character. The lower part of 

 these thin sandstones, or slates, generally includes heavier layers of 

 gray and variously colored sandstones, some of which are dark, others 

 lighter with green points ; some, too, fine-grained, others coarse and 

 gritty. Occasionally, bands of dark gray magnesian limestone, and at 

 some points calcareous slates occur, interstratified with the sandy layers. 

 The hard sandstones of this member form many sharp, straght, roof- 

 like, or " comby" ridges in East Tennessee. 



2. The Shale Member. — This is a heavy sub-group — many hundred feet 

 thick — of brownish-red, greenish, and buff, or variegated soft slates 

 or shales. It often contains seams and beds of blue oolitic limestone, 

 abounding in the remains of Trilobites. At some points the shales 

 themselves furnish Trilobites, as well as Lingular. This member occu- 

 pies numerous valleys, many of them rich and fertile, in East Tennes- 

 see. Its superior part, interstratified with the blue oolitic and Trilobite 

 limestone, gradually runs into the upper and following division. 



3. The Limestone Member. — This, too, is a heavy sub-group — perhaps 

 not less than a thousand feet in thickness. It is generally heavy- 

 bedded limestone throughout ; the lower part is blue, often oolitic, and 

 frequently striped with argillaceous seams ; the middle strata are usu- 

 ally dark gray, more or less sparry, and magnesian ; the upper, gray 

 cherty and likewise magnesian. Such at least is its typical character ; 

 at some points these subdivisions are not easily recognized. Knoxville 

 is mostly located on the upper portion, and interesting sections are ex- 

 posed with the limits of the city. Many of the rounded cherty ridges 

 of East Tennessee are composed of the same rocks. 



(3.) Chilhowee Sandstones and Shales. — 2. Quartzose sandstones of 

 Chilhowee, of the French Broad River, etc., etc.; 1. Sandstones and 

 sandy shales of Paint Mountain, etc. ; corresponding to the lower beds of 

 the Upper Mississippi. Age of the Potsdam sandstone, and often con- 

 taining the Scolithus linearis of the New York beds. 



Metamorphic. — (2.) Ocoee Conglomerates and Slates, {semi-metamor- 

 phic.) — 3. Conglomerates and slates of the Ocoee River ; 2. Semi-talcose 

 slates of Monroe, Blount, etc.; 1. Conglomerate and slates of the French 

 Broad, and of the mountains in Sevier. 



(1.) Mica Slate Group. — 2. Mica slates of Ducktown ; 1. Gneissoid 

 rocks of Washington, Carter, and Johnson, etc. 



9. Fossil Fishes of the Carboniferous Strata of Ohio. — Dr. J. S. New- 

 berry has given descriptions of several new fossil Carboniferous fishes in 

 the Proceedings of the Philadelphia Academy of Sciences, viii, 96. 



10. Cretaceous Fossils of Nebraska. — Messrs. F. B. Meek and F. V. 

 Hayden, M.D., have given in the Proceedings of the Academy of Sciences 

 of Philadelphia for April, descriptions of many species of Cretaceous Mol- 

 luscan fossils from Nebraska. 



