of the Age of the Red Sandrock Series of Vermont. 375 
____ “['Two specimens only have been obtained of a shell, which resembles 
_ Atripa Hemispherica, of the .Clinton group of the New York system. 
_ Prof. Hall informs me that he is disposed to assign both the Clinton group 
and the Medina sandstone to one geological period.—c. 8. a.]”* 
This letter of Mr. Hall’s Spe the same thing that is estab- 
t 
in the Taconic discussion, and most especially to Prof. Hall who 
has always been Dr. Emmons’s leading opponent. The officers 
of three different geological surveys, namely, the survey of Ver- 
most under Prof. , the survey of Canada under Sir W. E, 
Logan, and the recent survey of Vermont under President 
Hitchcock, have at different times all placed the Red Sandrock 
in the horizon indicated in the above letter. They were all in 
constant communication with him, and in the Introduction to 
the 3d vol. of the Pal. N. Y., he claims priority over them all 
In the authorship of the very same views which he now seeks 
to charge upon them. In this last named work (p. 14) he say 
are no doubt the fossils of the Georgia slates which are calle 
Trenton limestone in his sections. On page 16, he says: 
“The opinions advanced by the writer (meaning himself) in 1844 and 
1845, and published in the first volume of the Paleontology of New 
York, relative to the age of the rocks composing the metamorphic belt 
on the east side of the Hudson river, and including the principal part of 
the Green Mountain range, has been fully confirmed by Prof. Adams in 
the Geological Reports of Vermont. A re-examination of some portions 
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He then gives Canada credit for contributing a good deal to- 
wards the confirmation of his views and closes at the foot o 
16 with “Geological structure therefore, and chemical and 
tological evidence all unite in proving the age of these 
sta)? ; 
T shall only add that all the physical geologists engaged in 
this investigation with whom I have conversed on the subject, 
* See “Third Annual Report on the Geology of Vermont.” By C. B, Adams, 
State Geologist, éc., p. 31, er. Appendix O. 
