18 Geology and Mineralogy of a part of Massachusetts, &c- 
ground. Even the ledges of the rock at this place, Hcp 
appear firm, on being moderately struck, break o 
masses which fall to sand. No peculiar reason for the dis- 
integration at this place is known to exist. The rock, be- 
fore disintegration, appears to be the same as that at other 
places, where no such process is going on. This sand is 
employed in sawing marble into slabs, and in the manufac- 
ture of glass. It is said tohave been transported to the glass 
factory in Utica, N. Y. It appears to be inexhaustible, and 
is excellent for the composition of crown and cylinder glass. 
In several places in this section, there is a quartzose 
Breccia; or rock of conglomerated quartz. It is always 
connected with the quartz rock. About four miles from 
Pittsfield, in the S. W. part of Hinsdale, are large rocks 
compo osed of variously shaped, not rounded, Begipents of 
quartz cemented generally by Sibrous brown Hemat The 
iron ore is sometimes a mere lining of the fe " 
sometimes nearly half an inch thick. very m 
the aig of having been subjected toa high tempera- 
ture. Some have thought they discovered indications of 
an expired volcanoe. ‘This is doubtless mere imagination. 
In Great Barrington and Sheffield, the fragments are ce- 
mented by a quartzose cement, 
6. PRIMITIVE ARGILLACEOUS SLATE.* 
Colored Blue. ee 
This rock is found along the foot of the hills ofthe Taconick 
range of mountains. In Williamstown it forms considerable 
* | have vith mit rock primitive argillite, because it is - and 
primitive aca as s Bakewell has done. His great reason for doin _ 
is, t that as some be p 
itive, But ie ae argillite i is found i in the primitive rocks, and alternating 
With some of them, m, (Clea and’s Min. and Geol. p. 449 and 740,) there 
must be the same rea for ani dering it primitive, as for rankin 
kinds of limestone, greenstone, serpentine, &c. among min icra of the 
primitive formation. To remove all argillite into the transition and secon- 
dary rocks, is to blend the different rocks, and make the divisions, so gen- 
pra adopted, wi ithout the least use. The writer on organic remains in 
