386 
GEOLOGY OF THE FIRST DISTRICT. 
whole rock in some localities seems to be permeated by them, and the rock has an aspect 
almost trappean. 
Veins of quartz traverse all the rocks of the Hudson-river group more or less abundantly, 
but more frequently it is only the proper joints of the rocks that are filled with quartz and 
calcareous spar. 
Local details in Columbia and Dutchess counties. Rocks that have formerly been called 
grey wacke,Varying in texture from an argillaceous slate to a sandstone, succeed the limestone 
of the Fishkill valley about three-quarters of a mile from the village of Fishkill, on the old 
post-road from New-York to Albany. It seems to pitch under the limestone, though the con¬ 
tact was not seen. The dip is generally to the east-southeast from ten to fifteen degrees, but 
at Wappinger’s creek it is nearly vertical. Some quarries of the grit rock have been opened 
along "the road, for wall stone. It is easily quarried into rhombic blocks and fragments, in 
consequence of the joints that traverse the rock. 
The grit and slate rocks of the Hudson-river group are seen abundantly in place, three 
miles south of Poughkeepsie, on the post-road, and continue to be seen at intervals, emerg¬ 
ing in ridges and hillocks through the quaternary formation of the Hudson valley, to Hyde- 
park, Rhinebeck, Redhook, Clermont, Johnsville and Kinderhook. They are frequently 
interstratified with the slates, and sometimes with limestones and other rocks that will be 
subsequently mentioned under the heads of Utica slate, Trenton limestone, Calciferous rocks, 
and Potsdam sandstone. The strata dip at various angles from eight to ninety degrees, gene¬ 
rally to the east-southeast, but in some places to the northeast, and even to the north. The 
latter directions of the dip are local variations, due in most, if not in all cases, to derange¬ 
ments of the strata along transverse axes of disturbance. The rocks are traversed by veins of 
quartz and calcareous spar. 
Between Lower Redhook village and the landing, the grit rocks of the Hudson-river group 
were exposed to view, where in many places they emerged from the quaternary ; and in two 
places on the road, about three-quarters and one mile from the village, where the rock had 
been recently uncovered in making the road, well characterized drift scratches were observed^ 
The surface was smoothed off as if ground down by attrition,' and showed no inequalities but 
those of the scratches. The dip in all the localities was eastwardly at a high angle. 
Singular contortions of the grit and slate rocks may be seen on the shore a few rods below 
the landing. The rocks are bent, and folded, and packed together in such a way as cannot 
be easily described or represented. The strata are nearly vertical, and bent into regular and 
irregular curves and folds. The grit rocks, in strata from six to twelve inches in thickness, 
are interstratified with slaty grits and slate. The diagram, Plate 10, fig. 11, which is an im¬ 
perfect horizontal section, will give some idea of the arrangement of the strata. Between 
the warehouse and these contorted rocks, the grit rock is seen nearly vertical, immediately 
overlaid by nearly horizontal slate. The strata are very beautifully exposed to view between 
Redhook and Rhinebeck landings on the shore of the Hudson, and on the small rocky islands 
near the east shore. Smoothed and scratched surfaces may be seen where the rocks have 
