1SG9.] ' ' [Wincliell. 



stocked "with the criiioids of the Kaskaskia division of the Mountain lime- 

 stone, embracing Pentremites Godoni, pyriformis, symmetries and globosus 

 and Af/assizocrinus gihbosus. Tliis section is from tlie eastern border of 

 the basin of Tennessee along the road from Nashville to Sparta and the 

 summit of the Cumberland Table Land at Bon Air. 



A black bituminous shale exists in considerable force in Carrol county 

 and other parts of Arkansas, immediately superimposed by lower carbon- 

 iferous limestones ; but Dr. D. D. Ov^^en expresses a doubt vs^hether it 

 ansvpers to the Devonian Shale of Ohio ; and he also doubts the existence 

 of rocks in Arkansas corresponding to the Knob formation. 'O' 



In attempting to trace the parallelism of these formations on purely 

 structural and lithological grounds, it may be remarked, in the first place, 

 that the identity of the Black Shale cannot now be mistaken. It is a 

 matter of no surprise that it should at any time have been referred to the 

 horizon of the Marcellus Shale, as long as stratigraphical observations 

 were confined to Ohio and Indiana. Its stratigraphical position above the 

 Hamilton group is now, however, demonstrated by actual superposition 

 in Grand Traverse Bay of Lake Michigan, Thunder Bay of Lake Huron, 

 at various points in the peninsula of Ontario, and on the borders of the 

 "Knob region" below Danville in Kentucky. Its position immediately 

 below the arenaceous and argillaceous beds which are the subject of dis- 

 cussion in this i)aper, is demonstrated by the order of superposition at Pt 

 aux Barques of Lake Huron, at sundry points in Branch, Kalamazoo and 

 Allegan counties, Michigan, and at various places in northern and cen- 

 tral Ohio. When at Rockford, Indiana, I had the opportunity to make 

 my observations under favorable circumstances. The milldam had been 

 broken away by a freshet, and the exposure of Black Shale three-fourths 

 of a mile above was such as to indicate clearly by the dip, that this rock 

 passes under the Goniatite limestone. My observations in this vicinity 

 enabled me to determine the following succession of strata. 



Goniatite Bed — seen below the dam and at Wilson's creek. 



Semi-indurated clay. 



Limestone, fine, conapact but shattered, bluish, rusted in the vicinity of 

 the fractures. Contains the Brachiopods and Radiates described from 

 Rockford. 



Black Shale. 



It is further possible, as first suggested by Messrs. Meek and Worthen, 

 that the blue shale at the base of the Lithographic Limestone in Missouri 

 should be co-ordinated with the Black Shale. I think, however, there are 

 reasons for considering the Genesee Shale unrepresented in Missouri. 



It is proper to remark that the so-called Black Shale or " pyroschist "'"^ 



'<" Geology Reconnois. Ark. I, pp. 87, &c., and 135. 



102 Dr.T. S. Hunt proposes this Atiglicised Grsecism of the "Brandschiefer" of the Germans, 

 (Amer. Jour. Sci. [2] xxxvi., 159,) since, as he asserts, this shale contains no free bitumen. ]n this, 

 however, he Is certainly mistalcen, as I have seen it oozing from the cliffs in Grand Traverse Bay ; 

 and I am informed that the odor has sometimes attracted the attention of travelers. It appears, 

 furthermore, that the intimate mingling of comminuted organic matters with argillaceous ma- 

 terials creates the most favorable conditions for the spontaneous evolution of hydrocarbonaceous 

 products from the rocks. 



