Geology and Natural History. 469 
sition. Again, on page 147, after having spoken of the three 
mestones and discussed the question whether they might not be 
repetitions of the same formation, he decides this question ad- 
North A limestone, the most eastern rock in his section, the 
most recent. He concludes his chapter on the Taconic by the 
statement that “the Taconic rocks appear to be equivalent to the 
Lower Cambrian, and are alone entitled to the consideration of 
But during the year following the publication of the Geo ogical 
Report of 1842, Prof Emmons met with a new discovery, and in 
Consequence made most desperate bineiecite in American 
eology. He found a “ Black Slate” at Bald Mountain, mn Co- 
umbia Co, N. Y, (west of Berkshire), to contain fossils. As the 
locality lay to the west of the Taconic, it seemed to prove, on the 
being put d : es,” and in figs. 2 and 3 the houndary is 
: : Bits, heath oe toe eg on ote 138 ‘Lite volume, the distinction 
of the Taconic from the Hudson river shales or slates adjoining (or “ upper mem- 
i of the Champlain group”) is particularly dwelt upon. The extension of the 
Taconic to the Hudson river, so as to include the “slates and masses of the 
tn amplain group.” appears first in Prof. Emmons’s Agricultural Report, published 
* Prof. Emmons says that the strike of the rocks is very uniformly between 
N. 10° W. and N. 10° E., and the dip throughout easterly, averaging 30° to 35°. 
The dips he regards as a result of monoclinal uplifts (pp. 141, 142). 
