= 7 Geology of Massachusetts. 
places, I have endeavored to obtain specimens from each locality. 
I have collected likewise, all the ores of importance found in the 
State, as well as the other simple minerals, which could be obtained 
without much difficulty or delay. I did not suppose that my instruc- 
tions authorized me to be at much expense and trouble in procuring 
every rare mineral that has been described as occurring in the State; 
although this object may still be accomplished, if I have mistaken the 
intentions of the Government. The collection of specimens, which 
I have already made for the use of the Government, contains seven 
hundred and eighty individual pieces: and it is not yet completed ; 
so that I shall not be able to forward it with this part of my Report. 
- I do not know to what use the Government intends to devote this col- 
lection. But supposing it would be placed in some public situation, 
in order to exhibit to the citizens the geology and mineralogy of the 
State, I have endeavored to obtain from all the important quarries, 
and beds, whence stones are obtained for the purposes of architect- 
ure, or ornament, specimens which would fairly exhibit the qualities 
and value of each. : 
I have'also in accordance with my instructions, endeavored to 
collect all the important varieties of rocks and minerfs in the State, 
for the use of each of the colleges in the Commonwealth. 
I cannot hope to complete more than the firstipart of my Report 
the present season: since some further points remain for investiga- 
tion, before the third part can be properly finished. 
In presenting a view of our economical geology, I shall first make 
a few remarks upon the different soils found in the state, as connect- 
ed with the rocks over which they lie. And since it is an acknowl- 
edged fact, that all $6ils, had their origin in the disintegration, or de- 
composition of rocks, it might seem easy, at first thought, to ascer- 
tain the nature of the soil, if we do but know the integrant and constit- 
uent parts of the rock underneath it. Thus, in a soil lying above 
granite, we might expect that siliceous sand would be the predomi- 
nant ingredient; next, clay with small quantities of potash, lime, 
magnesia and iron; because these are the constituents of granite. 
But several causes so modify soils, as to render all conclusions of this 
kind extremely uncertain. In the first place, the character of a soil 
depends more, in general, upon the nature and amount of the vege- 
table and animal matters it contains, than upon the nature of its other 
ingredients. And in the second place, the agency of running water, 
not merely of existing streams, but of mightier currents, to which 
the surface has been exposed in early times, has been powerful 
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