531 
companied by the first geological map of that country, were read 
to the American Philosophical Society in Philadelphia, Jan. 20, 
1809, and published in the sixth volume of their Transactions, part 1. 
In these Transactions also (vol. i. New Series) he published a se- 
cond paper, read May 10, 1817, upen the same subject, with a 
geologically coloured map and sections, in which his views were 
improved and ‘corrected by eight years’ additional observations in 
the United States, and by a geological tour over a great portion of 
Europe. 
This admirable paper was reprinted at Philadelphia in 1817, in a 
separate Svo volume, entitled, ‘“ Observations on the Geology of the 
- United States of America, with remarks on the effect: produced on 
the nature and fertility of soils by the decomposition of the different 
classes of rocks.” 
On this important subject, of the connexion of geology with 
agriculture, Mr. Maclure has clearly shown that the fundamental 
basis of the agricultural resources of every country must rest on 
the condition which its soil derives from the rocks or strata that 
have supplied the materials of which it is composed ; and wisely 
profiting by his suggestions, the different governments of the United 
States have caused geological surveys to be made of their respective 
districts; fully aware that not only the agricultural condition. of 
every country must depend on the nature of its soil; but its future 
capabilities of: becoming ‘the site of extensive manufactures must 
also mainly depend on the presence or absence of subterraneous 
stores of fossil fuel. 
Mr. Maclure’s publications upon the geology of this most import- 
ant part of the Western Hemisphere are marked with the finest ap- 
preciation of the just philosophical principles of geological research, 
and a spirit of combination and generalization of the largest and 
boldest character, yet never running wild. His map, which pre- 
sents the synoptical result of the whole, is unrivalled by anything 
produced before that time. Adopting the Wernerian arrange- 
ment, he is far superior to Werner in the philosophical character of 
his mind; his colours represent primitive, transition, secondary, 
and what he calls alluvial, which are mostly tertiary, on the east of 
the Alleghany chain. Under this class he has ineluded the lower 
cretaceous formations of New Jersey, which he remarks may pro- 
bably prove to be secondary.’ The great simplicity of the: struec- 
ture of America, and more extensive continuity of its formations 
as compared with those of Europe, greatly facilitated his task ;. his 
map is therefore a very near general approximation to what: would 
even now be given; his secondary rocks include what would now 
be called Silurian and Carboniferous, and he notices the absence of 
the chalk of Europe and of the Jura limestones. Of course he 
could not enter into the distributions of the Silurian and Carboni- 
ferous groups; but he observes, that a red sandstone seems the 
basis of the whole, and this he calls old red. The more exact local 
description of portions of the Carboniferous and Silurian groups, 
and the identification of the lower cretaceous deposits of greensand 
