112 S. F. Peckham—The Origin of Bitumens. 
bonie acid and nitrogen, while the latter consist mainly of 
rsh-gas. Bitumens are not the product of the high temper- 
atures and violent action of volcanoes, but of. the slow and 
gentle changes at low a sie i to metamorphic action 
upon strata buried at immense de 
The extent of the Paleozoic Seaton of the Mississippi 
valley, and the general conformation of the bottom o he 
ancient seas, has been fully described by Professor James Hall.* 
He says: “In all the lower Silurian limestones we trace the 
and thence still in the same auiicioatenke direction. 
_ stead of finding the lower Helderberg (Upper Silurian), strate 
l 
in lines peeps with those of the preceding rocks, the relative 
direction of the main accumulation and the pr rincipal line o 
The li 
a acie is diagonally across the others... . e line of 
outcrop and of accumulation has been from northeast to south- 
west, and they occur in great force far to the northeast in 
Gaspé, on the Gulf of St. Lawrence. eatest accum- 
ulation of materials in the period of the Hamilton, Portage 
and Chemung groups (Lower and Middle Devonian), lies in 
the rian of the Appalachian chain. . . . In Gaspé there 
are 7000 feet of strata, ... while in western New York the 
whole ig wees would not ‘exceed 3000 feet. We have, there-— 
pas ee et have ti since shown that... the portion 
of the Appalachians known as the Green Mountain ane is 
composed of altered sediments of Silurian age. . . . The evi- 
dences in regard to the White Mountains, to a great ‘extent ae 
of newer age than those of the Green Mountains, or Devonian 
and Carboniferous. . . . The statements of Sir William Logan 
in regard to the great accumulation of strata in the peninsula 
of Gaspé, together with the observations of Professor Rogers in 
the Appalachians of Pennsylvania, lead to the inevitable con- 
* Nat. Hist. N. Y. Potash iii, 45-60. 
Nely 
