T. N. Dale—Clay-slates and Grits of Poughkeepsie. 57 
Art. VII.—On the ws of the Clay-slates and Grits of Pough- 
keepsie ;* by 'T. NELSON DALE, Jr. 
In Mather’s geological sections of the Hudson River valleyt 
the alternating argillaceous schists, slates and grits, on both 
sides of the river, in the vicinity of Poughkeepsie are assigned 
to the Hudson River roup. This term was originally intended 
to include the series between the Utica Slate below and the 
Medina Sandstone above. These rocks would thus represent 
the uppermost North AtneTget. 3 HONE ilurian. 
In the geological map drawn by Logan and Hall, and 
appended to the Report of Fig eet Geological Survey, 
the rocks for some miles on both sides of the Hudson River, 
south of Rondout on the west side and of Rhinebeck on the 
east side, and extending southward beyond Poughkeepsie, 
are designated as Calciferous and Quebec. They are 
aig to the middle division of the North American Lower 
i pan 
Dana, referring to this subject, observes in his Manual of 
Geology, ed. 1874, on page 184: “ The gee of the Que- 
€c group southward, along the west side of the Green Moun- 
tain range, covers, according to Logan, a cihedarable part of 
New York east of the Hudson, the rock being part of the non- 
fossiliferous clay-slate (formerly called Hudson River slate) 
which outcrops near Poughkeepsie, ete. The area is divided 
_ Epoch: “In New Yor ie the Hudson River els include ainlee 
and sandstones. They are the Lorraine shales of Jefferson 
County (the Pulaski shales of the New York Annual Reports), 
containing some thin beds of limestone. The slates along the 
udson River, to which the name was especially applied, ‘have 
been prove to be in part Primordial, and part, probably of the 
Quebec se 
These cor have therefore been first assigned to the Trenton 
Period, then to the Canadian Period and afterwards declared 
paper tee ai the substance of this article, in a different form, and 
ted * “A contribution to the Paleontology of the vicinity of Ponghkedbele” a was 
read by the author before the Poughkeepsie Society of Natural Science on Decem- 
ber 4th, 1878, and is being published in the Proceedings of 
ty. 
ie t. Hist. oN. Y., Part [V, Geology, by William W. Mather; Plates 16, 18, 
