Origin of Anthracite. — Keyes. 411 
The ready discovery of folds in the Lower Coal Measures 
is, as a rule, a matter of considerable difficulty, and, indeed. 
they can only be accurately traced in exceptional cases, such 
as the one described, in which easily recognizable beds are 
present over a considerable territory. 
Striking as the contrast between the Mystic and other coal 
seams of the region is, as regards the extent and simplicity of 
structure, the remarkable uniformity of its physical character- 
istics is no less noticeable. In hand specimens the coal, 
though rather soft, is clean, and presents a smooth, glistening 
surface with a luster almost indistinguishable from that of 
anthracite. It is intersected by numerous joint planes cross- 
ing one another at right angles and filled with thin films of 
ealcite. 
It has been said that the limestones which are found near 
the coal seams are quite fossiliferous. As might be expected, 
the}' present a well-marked marine facies. In some instances 
certain of these species are found in the shale which immedi- 
ately overlies the coal. Frequently this shale graduates in- 
sensibly into a bituminous limestone. The peculiar constancy 
of physical character, exceptional in western coals, and the in- 
timate relations with marine strata, lend a certain suggestive 
interest to the theory proposed by Mohr* for the origin of coal 
under maritime conditions. While his idea that coal was 
formed from sea- weeds has never received much support in 
this country, it seems not impossible that for certain particu- 
lar seams, admittedly formed under peculiar circumstances, 
this may be found an adequate explanation. 
ORIGIN OF ANTHRACITE. 
By Charles Rollin Kkves, Dee Moines. Iowa. 
The transformation of woody tissue into ordinary coal in- 
volves a continual loss of the hydrocarbons which go to make 
up so large a proportion of the original plant mass. As the 
ultimate result of the process anthracite is formed. While 
the exact physical conditions necessary to effect tin- changes 
are not yet perfectly understood, it i< well known that the 
last stages of mineralization may be arrived ;it in a variety of 
*Geschichte der Erde. Bonn, 1875 
