Geology of Massachusetts. 11 
decomposing carbonate of lime upon the soil. Indeed, I believe that 
it is generally thought in Europe, that soils of this Berne 3 are 
more productive than any other, except rich alluvions. d 
prehend that one of the greatest deficiencies in the soil of the cine 
pal part of Massachusetts, is the absence of lime. Probably if our 
farmers could procure this article at a moderate expense, its applica- 
tion as a manure would amply reward them for their trouble. Lime- 
stone that contains much magnesia, is, indeed, said to be injurious 
to vegetation, unless it be upon peaty soil, or soil containing much 
vegetable matter ; and this limestone is common in Berkshire Coun- 
ty. But it occurs there in beds, alternating with the pure carbonate 
of lime, and I apprehend rarely produces any bad effect. : 
Quartz Rock, 
It will be seen at the map that one variety of this rock is associ- 
ated with mica slate, and another with gneiss; so intimately, indeed, 
that its agricultural character may be considered the same as that of 
these rocks. When it occurs in the state of pure quartz, it is so lit- 
tle acted upon by es common decomposing agents, such as air, heat 
and moisture, as to exert little or no influence upon the superincum- 
bent soil; except in the town of Cheshire, where it produces a pure 
white sand. ; 
Chlorite Slate, Talcose Slate, Mica Slate. 
The first of these rocks occupies too little space to deserve any 
notice in respect to the soil resulting from it. ‘The second is in gen- 
eral a mere variety of mica slate, talc taking the place of mica, or 
being superadded to it. Where the talcose slate, however, is most 
pure, so as in fact to be little else but slaty talc, with more or less 
quartz, the soil which its decomposition produces, is decidedly infe- 
rior to that-resulting from mica slate ; and probably this is owing to 
the large quantity of magnesia which tale contains. » 
Mica slate produces a soil of a medium quality. Some varieties 
of it underlie tracts of superior quality. Butthe most extensive tract 
of mica slate in Massachusetts, consists of the high and mountainous 
region west of Connecticut river : so that it is difficult to compare the 
a lying over it, with that of formations at a lower level. The deep 
avines, however, so common in the mica slate, furnish many very 
fertile though limited patches of ground ; while the mountain sides 
are very superior for grazing. 
