was then not under the in until the commencement 
to be the case from the following facts : 
Ist. Within an area which I know to be from 40 to 50 miles from 
east to west - ~~ 80 from north to south, the black slate, wherever 
it is irectly upon rocks of the Hudson period, the inter- 
mediate upper Silurian and Devonian beds being absent. This may be 
— in = by referring to my geological map of Tennessee. 
re the absent rocks first appear around the area —— 
cer have an n inconserable feronacies often but a few feet, thi 
hey as we approach the supposed ancient land, and thickening x 
said anifoemiy in the opposite —, » thereby separating more and 
more the black slate and low urian 
3d. No evidence of the denndation of “the absent rocks, previously to 
the deposition of the black slate has been observed. 
Upon the whole I think there is good reason to believe that such an 
e distance from. the land increased. On the west and south 
= tten. sig Si tone ‘those drawings. have not been found. 
are er Mr. ae descriptive notes of several 
a Ci es al 
small monograph on Chonetes was then ha 
printed, but | which still r unfinished. ae 
My attention was not especially directed to a comparison of these fos- 
sils with organic remains peculiar to rocks of the Permian system, as 
"SECOND SERIES, Vou. XXVI, No. 76.—JULY, 1858. 
17 
Geclogyand Mineralogy. 129 
age, an sea again until nt of 
the bon pout which the “black slate” was ieadnd: Such I infer 
