Geology and Mineralogy of a pari of Massachusetts, &c. 29 
Canaan and Cornwall, to: Washington, Con., and thence 
through Brookfield, &c., to Reading, in the same state. 
See Geology of the Northern States, page 158. 
The western range seems to be separated from the 
eastern in Canaan, Con., by a hill of mica-slate along the 
east part of Salisbury. ‘This mica-slate belongs to the 
same stratum which separates the two ranges farther north. 
The western range of limestone is therefore continued from 
Sheffield through Salisbury, and along the adjacent parts of 
Connecticut and New-York. The general course of this 
range, if continued, would pass near Kingsbridge, in the 
neighborhood of the city of New-York. And as granular 
limestone is found along this course in some of the coun- 
ties north of Kingsbridge, it is very probable that the lime- 
stone of Kingsbridge belongs to this range of limestone. 
‘These considerations render it improbable that the High- 
lands of New-York, belong, geologically, to the ranges of 
mountains in New-England. The rocks of the Highlands re- 
resemble those of the range east of the Taconick range; so 
that, if they belong to our mountains, the granular limestone 
of Berkshire county must lie on the western side of this 
range of mountains, and most of that in Connecticut, and at 
Kingsbridge. must lie on the east side of the same 
range. Such a supposition is opposed by those ob- 
servations which have shown the continuity of the granular 
limestone of Berkshire county, in nearly a direct course 
towards Long Island Sound. An examination of this part 
of the state of New-York, would indeed be the experimen- 
tum crucis, and will amply repay him who shall be able to 
do it. ‘This examination is very desirable, to settle with 
certainty several points in our geology. 
In the examination, it will be necessary to trace the 
transition argillite south of Columbia county, and to ascer- 
tain whether it be limited on the south by the primitive 
rocks of the Highlands. This examination must be ex- 
tended eastward of the Highlands, over the counties of 
Dutchess and Putnam, to the line of Connecticut. The 
remarks on the geology of Dutchess Co. in Bruce’s Mine- 
ralogical Journal, are too brief, and were not designed to 
throw any light on this particular point. From the notice 
of the Highlands, in this Journal, Vol. V. p. 232, it would 
seem that the gneiss of this interesting place rises up 
