CHAMPLAIN DIVISION. 
391 
These slate rocks form a large proportion of the slate of the Hudson valley. They may 
generally be distinguished by their dark and black color; but there are some strata among 
the grits of the Hudson-river group, that can scarcely be distinguished from these. They 
range through the State from Vermont to New-Jersey, and in fact from Canada across Vir¬ 
ginia. They are well exhibited to view on the banks of the Hudson above Newburgh, and at 
Fishkill landing. Blue point, Marlborough, Poughkeepsie, Hudson, Troy, Baker’s falls, and 
many places along the shores to Lansingburgh ; on the Mohawk, at Cohoes falls and below; 
on the railroad from Schenectady to Ballston ; also in the village of Ballston-spa ; in Kings¬ 
bury, Washington county, between Sandyhill and Fort-Ann. 
Search for Coal in the Utica slate group. 
The slate of this group is often black, highly carbonaceous, glazed with anthracite, and 
contains thin seams and small fragments of this combustible. 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 necessarily be found below. 
Some of the localities where excavations for coal 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 outcropping edges of beds of 
anthracite. In some localities vegetable remains are found, and the slate is glazed with films 
of brilliant anthracite. There are, at least, five species of fucoids, among which Mr. Conrad 
recognized the Fucoides dentatus and Fucoides serra. One species of trilobite, which will be 
described, was also found in the fissile slate. 
About one mile south of Hudson, an excavation has been made for coal. Some of the 
rocks might be mistaken for coal, by those who are not minutely acquainted with coal and its 
varied aspects. The slate is highly impregnated with carbon, the fissures being filled with 
thin films of anthracite, and small pieces of this combustible of the size of a pea are not 
uncommon? This slate strongly resembles the impure anthracite and anthracitic shales of 
some of our coal mines. Graptolites are abundant and very beautiful at this locality. 
At Rider’s mills in Chatham, Columbia county, both the slate and limestone are glazed 
with anthracite; and these materials having been excavated from a mill-race, induced high 
expectations of the value of the coal mine that was believed to lie below, and which was 
supposed to be bituminous coal. Mr. Rider was offered a large sum for his farm, which he 
refused in consequence of the supposed value of the mine. 
Two excavations have been made for coal, near the line between Canaan and Austerlitz : 
one on the farm of Elisha Lord, in Austerlitz; the other on Joseph Olmstead’s land, in 
Canaan. At one of these places, a company in New-York expended eleven hundred dollars. 
They bored about one hundred feet, and in that depth passed through five inches of carbona¬ 
ceous or plumbaginous slate. The rocks of these hills are talcose and chloritic slates. 
