6 BULLETIN 64, UNITED STATES NATIONAL MUSEUM. 



strata in which they occur are more or less inclined, but they assume soon a horizontal 

 direction. I consider these strata as belonging to the lower division of the Silurian sys- 

 tem, being characterized by Calimena Fisheri, which are found in the vicinity of Knox- 

 ville. This series extends northwards to the State of Virginia. The ridge which runs 

 parallel to Bay's Mountain and which commences in Knox County traversing Granger 

 and Hawkins Counties, where it forms the Clinch Mountain and which is principally 

 composed of sandstone and aluminous slate, containing extensive deposits of cala- 

 mine and hydroxide of iron, seems to be analogous to Bay's Mountain. « 



I have not yet determined to which division of the Silurian system the strata of 

 limestone east of the Cumberland Mountains belong — It is very probable that they 

 belong to the lower division — perhaps they are equivalent to what Murchison calls 

 Llando [probably Llandeibo] flags. I found in some the Calimena Fisheri, etc.b 



The above described formations are separated from the more western (which form 

 Middle Tennessee) by the Cumberland Mountains which traverse the State of Ten- 

 nessee in a south east [west] and north west [east] direction, and are composed of a 

 series of parallel ridges known under the names of Walden's Ridge, Craborchard Moun- 

 tain, Cumberland Mountain, Brimstone Mountain etc. They all belong to the Car- 

 boniferous formation and are formed of limestone, sandstone and coal strata. Near 

 the Craborchard the limestone stratum [Bangor limestone] pierces through the super- 

 incumbent sandstone. It is of oolitic structure and is characterized by Demonocrinites 

 [Talarocrinus symmetricus] and by those Pentremites which characterize the Carbonif- 

 erous limestone in Kentucky, Tennessee and Alabama, and it forms generally the 

 base of that mountain. It is particularly displayed near Sparta, where the whole 

 stratification is visible. The Sequatchie Valley displays also the stratification of this 

 mountain. The bottom of this valley, through which winds longitudinally the Sequat- 

 chie River, is generally of Silurian [Ordovicie] strata of two different ages. The south 

 eastern side of the valley is composed of the Silurian strata which prevail in East Ten- 

 nessee [Knox dolomite] and is covered by the limestone which is found in Middle 

 Tennessee, [Ordovicie limestone] so that the junction of the two divisions takes place 

 in this valley and continues below the Cumberland Mountains. 



The country west of the Cumberland Mountains as far as the Tennessee River, known 

 under the name of Middle Tennessee, is generally composed of Silurian [Ordovicie] 

 limestone which is here and there covered by Carboniferous and Devonian Strata. 

 Most of my observations being made before I was acquainted with the labours of Mr. 

 Murchison, I can not give an accurate limitation of the Devonian and Carboniferous 

 deposits, so that some of the Crinoids which are put down as occurring in the Carbo- 

 niferous strata may belong to the Devonian deposits. The Middle Tennessee rocks 

 terminate at the Tennessee River. At a few places they cross this river, as in Decatur 

 County. Nevertheless this river forms generally the western limit of the Paleozoic 

 Strata in Tennessee. 



West of the Tennessee River, as far as the Mississippi which forms the western bound- 

 ary of the State of Tennessee, the Cretaceous strata prevail. [See above p. 4]. They 

 are composed of marl, green sand and argileaces strata, the first [Selma clay] charac- 

 terized by Exogyra costata, Gryphaea convexa and several species of Ostrea — the second 

 (green sand) by Hamites and Ptychoceras, and the third [Ripley formation] by siliceous 

 wood and lignite. 



o Clinch Mountain is composed of Ordovicie and Siluric strata ranging in age from 

 the Knox dolomite to the Rockwood formation, while the strata of the Bay's Mountain 

 region are Cambric and Ordovicie, in age ranging from the Athens shale to the Bays 

 sandstone. — E. W. 



b The formations east of the Cumberland escarpment have been mapped by the 

 U. S. Geological Survey as the Knox dolomite and the Chickamauga limestone. — E. W. 



