CHAMPLAIN DIVISION. 
385 
Columbia and Dutchess Counties. 
The rocks of the Hudson-river group, and of nearly all the Champlain division, are remarka¬ 
bly well developed in these counties. They are well exposed to view, and capable of rigid 
examination and identification in the bed and banks of Kinderhook creek, from Valatie to its 
mouth; the banks of the Hudson, near the city of Hudson ; at the base and on Merino moun¬ 
tain, to the southwest of Hudson; the rocky island called Rogers’s island, between Hudson 
and Catskill; the rocky shore of the Hudson river, from the mouth of Ancram c/eek to Red- 
hook ; the rocky islands below Redhook landing, and from Redhook landing to Barnegate. 
The rocky shore of the Hudson above mentioned, offers better opportunities for a rigid examina¬ 
tion of the rocks of the Hudson-river group, with their derangements, contortions, wrinklings, 
faults, and cleavage planes, than any equal portion of the country I have examined; and I would 
recommend to those who wish to study the rocks of this group, and their derangements, to take 
a row boat, and examine this shore attentively. It will amply repay every one who takes any 
interest in practical and physical geology. 
A few of the phenomena alluded to above, are partially illustrated by the diagrams on Plate 
9, figs. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 20, 21; Plate 10, figs. 2, 3, 6, 7, 8, 9, 10, 11 ; Plate 
24, figs. 1, 2, 3; Plate 29, figs. 1, 2; and Plate 38, figs. 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12.* 
The country back from the Hudson also presents very fine opportunities for studying these 
strata wherever they are uncovered. They consist of slaty and thick-bedded hard tough grits, 
shale and slate, the latter often changed to siliceous slate and basanite, in the vicinity of quartz 
and other intrusive veins. These rocks range through the western half of Columbia county, 
and the townships of Redhook, Milan, Rhinebeck, Clinton, Hydepark, Pleasant-valley, 
Poughkeepsie, Lagrange, and the northwest part of Fishkill in Dutchess county. 
Most of the grits are calciferous, so as to efifervesce slightly with a strong acid, when taken 
from a sound rock that has not been exposed to weathering. The grits, shales and slates are 
interstratified, alternating a great number of times, like those on the Mohawk river and Scho¬ 
harie kill. They are mostly composed of fragments of the lower rocks of the Champlain 
division. 
The coarse greenish grit that occupies so prominent a place in- Rensselaer county, is also 
an important rock in Columbia county, but is not so coarse-grained, and becomes finer farther 
south. It forms a mountain mass, extending from the northwest corner of New-Lebanon, 
through the east part of Chatham, west part of Canaan, Austerlitz, west part of Hillsdale, 
Taghkanic and Gallatin in Columbia county; and Milan, Redhook, Rhinebeck, Clinton and 
Hydepark in Dutchess county. 
Veins of quartz abound in this rock, and in the northern part of Columbia county. The 
* I spent a considerable time in meandering and examining the shores of the Hudson, encamping every night wherever the 
darkness overtook me. Most of the notes of the sections and observations made were accidentally lost (blown away in a gale of 
wind). 
Geol. 1st Dist. 49 
