2 The American Geologist. July, 189 
present pajxT being practically acquainted with the anthra- 
cite region of Pennsylvania, as well as possessing some field 
and book knowledge of the principal anthracite fields of Eu- 
rope, is induced to put his notes into tangible shape for the 
purpose of showing that the theory advanced by Dr. Steven- 
son does not sulliciently explain certain phenomena of anthra- 
cite regions, and of that of Pennsylvania in particular. 
It may be well to state Dr. Stevenson's hypothesis briefly. 
He considers that the anthracite of Pennsylvania was origi- 
nally vegetable matter similar to that of which the bitumin- 
ous seams of the western part of that state are formed, but 
that the coal is not now bituminous because the accumulation 
of vegetable matter in the eastern area remained exposed for 
a longer period to the agencies which formed coal (before 
being covered up with sediment) than those of the western 
area. So that the inference is that Stevenson does not con- 
sider the partial metamorphism to which the anthracite series 
of Coal Measures have, as a whole, unquestionabl}'^ been sub- 
iected, has been instrumental in converting the once bitumin- 
ous coal into semi-anthracites and hard dry anthracites. 
II. Evidences of Metamorphism in Pennsylvania An- 
thracite. 
Now, the writer does not dispute a practically the same 
vegetable origin of anthracite as of bituminous coal. The 
first thing to consider is, what evidence is there that the 
Pennsylvania anthracite Coal Measures have undergone any 
metamorphosis? Aside from the general references made by 
Rogers, Dana, Le Conte, Lesley, Hunt and others in their 
manuals, text books, etc., the observations of the writer war- 
rant him stating: 
a. The fire clays of these coal regions are much more com- 
pact, less affected by weather, and heavier and tougher than 
those of the regions further to the west. 
b. The shales (appropriately termed "slates") are very 
dense, hard and but little affected by exposure. 
c. The sandstones and grits are exceedingly compact, tough 
and generally heavier and darker than in bituminous regions. 
Prof. T. G. Bonney reports observing a quasi-gneissic struc- 
ture in specimens sent him. 
