352 
GEOLOGY OF THE FIRST DISTRICT. 
formably upon the subjacent slate rocks. I have traced these rocks to within a few feet of 
their junction in many places. Over a large part of Becraft’s mountain, the strata slope from 
one to six degrees, both from the east and the west, towards the centre of the mountain, form¬ 
ing a very small segment of an inverted arch; and as the limestone is cavernous, and inter¬ 
sected by numerous fissures, most of the water which falls upon the mountain sinks into them, 
and is retained.* This peculiarity gives rise to a large limestone spring, which breaks out 
from the cliff on the north end of the mountain. It affords a constant and abundant supply 
of wholesome water for the city of Hudson. 
The lower beds of limestone of Becraft’s mountain are compact, of a dark blue, or nearly 
black color, and belong to the Water-lime group, and they break with a conchoidal fracture. 
The rock is easily dressed with a hammer, and is used for a building stone. It is beautiful 
and durable. The new Presbyterian church in Hudson is built of this material. Quarries 
have been extensively wrought in these beds, on the west side of the mountain. It has also 
been used for making lime. 
The middle beds of Becraft’s mountain are slaty limestones, and filled with fossil remains. 
Some layers are suitable for building, but generally they are adapted only for common wall 
stone. This is the same as the Catskill shaly limestone. 
The upper beds of limestone in this mountain are distinctly crystalline, and replete with 
fossil remains. There are several quarries in these beds near the summit of the mountain. 
The stone is mostly employed for rough wall stone, for basement walls ; and some of it has 
been used for making lime, for which purpose it is well adapted. This stone receives a high 
polish, and makes a beautiful grey marble with a tint of red. I have seen chimney pieces 
which were made of this material, that were very beautiful. Mr. Charles Darling, of Hudson, 
wrought one of the quarries as a marble some years ago, but the demand was not sufiicient to 
justify its continuance. The following description is an accurate one, as might be inferred 
from the distinguished author of it. Prof. Silliman. 
“ The marble is of a greyish color, with a slight blush of red; its structure is semicrystal¬ 
line, and in some places highly crystalline, especially in and around the organized bodies, 
which in vast numbers it embraces. Among them the encrinite is very conspicuous and fre¬ 
quent ; and when the marble is polished, the organized bodies congealed in a bright calcareous 
bed, and often more brilliant themselves than the medium in which they are fixed, give it a 
very fine effect. This is particularly true in large slabs, which present a great diversity of 
appearance, and could scarcely be distinguished from the similar transition marble of the Peak 
of Derbyshire, which it greatly resembles, and quite equals in beauty and firmness.” {Silli¬ 
man’s Journal, VI. p. 371.) 
Vide Plate 24, fig. 6; and Plate 38, fig. 1. 
