No. 200.] 
163 
shore of the Hudson river, from Upper Red Hook Landing to Hyde 
Park. 
The varieties of this rock which have been quarried are interstratified 
in many places with slaty gray wacke, graywacke slate, graywacke shale, 
brecciated limestone, compact limestone, argillaceous limestone, and a 
calciferous graywacke. 
Some of the talcose slate rocks contain much plumbago, and may be 
called plumbaginous slate. It is frequently seen on Hancock mountain 
near New Lebanon Springs. It has been used to diminish the friction 
of the wheels of carriages. 
Roof slate is frequently carbonaceous and passes into graphic slate. 
A locality of this slate is in the road near Mr. Asa Pelton's, and near 
the line betw^een Austerlitz and Hillsdale. It had been described to us 
as a locality of black oxide of manganese. This variety of slate also 
occurs on the mountain one and a half- mile south of Hillsdale, in 
Ancram, one-half mile to one mile west of the lead mine, and in many 
other places, but is not so black in these two last localities as in other 
places. It breaks out in columnar fragments. Much of this columnar 
slate is similar to pencil slate, and might probably be applied to this use. 
Many of the slate rocks of Columbia and Dutchess counties are so 
loaded with carbon, either disseminated or in thin films of anthracite, 
which fills the natural fissures, cleavages, and breaks of the rock, that 
many persons have expended time, labor and money in digging for coal. 
Too many adopt the plausible idea that if a little of the mineral which 
is sought be found on or near the surface, extensive beds must necessa- 
rily be found below. 
Some of the localities where excavations have been made are well 
calculated to deceive those who are not professional geologists and 
mineralogists. In some of them, small layers and lumps of anthracite 
are actually seen; in others, the rock breaks into irregular fragments 
which are invested with a film of this combustible, and the fragments 
present an aspect somewhat similar to the carbonaceous matter near the 
out cropping edges of beds of anthracite. In some localities vegetable 
remains are found, and the slate is glazed with films of brilliant anthra- 
cite. Mr. Conrad, the palaeontologist of the survey, is investigating 
these fossils. There are, at least, five species of fucoides, among which 
Mr. Conrad recognizes the fucoides dentatus and fucoides serra. One 
species of trilobite, which Mr. Conrad will describe, was also found in 
