Observations on the Ocnn-rence of Anthracite. — Gresley. 3 
d. The conglomerates — composed chiefly of white and gray 
quartz pebbles with a few" of schist, slate, qnartzite, etc. — are 
extremely compact and dense; occasionally the adjacent peb- 
bles have been partially deformed or squeezed so that they 
are jammed into each other apparently without fracture. 
Through these conglomerates thin quartz veins sometimes run 
which pass right throiigh the pebbles, the latter exhibiting a 
melted or fused appearance w^here incorporated in the veins. 
e. The coals are very hard, compact, glassy and weather- 
resisting. 
/. The clay-ironstone nodules are very tough, dense and 
hard. They contain distinct zones of mineralization, and 
crystalline pju'ite similar to that found in similar nodules in 
the Alps is common in them. Their very dark color resembles 
both the Swiss and the Pembrokeshire nodules. 
<j. One characteristic of the fossils of this region is their 
black-leaded color or greasy metallic lustre, also observable in 
the slates of Rhode Island, Massachusetts and of the Alps. 
h. The quantity of occluded gas existing in anthracite, 
considering its apparent freedom from interstices and cellar 
structure, is remarkable. 
i. Carbon impregnation, such as streaks of graphite, and a 
more or less general pervasion of diffused blackening through- 
out the series. 
,;. Fine crystals of amethystine quartz have been found near 
Pittston, masses of lead and zinc ores in fissures in the coal 
beds near Scranton, smoky and clear quartz crystals near Ta- 
maqua; very hard and brilliantly crystallized pyrite has been 
extensively found near Pittston. 
Viewed as a whole these anthracite Coal Measures are of 
greater specific gravity, more crystalline, more siliceous, 
tougher, harder and darker than those of the western coal 
field of Pennsylvania. 
III. Objections to Stevenson's Theoky. 
1. Cheudcal considerations. In order to agree with this 
theory facts ought to show that the percentage of volatiles in 
the anthracite decreases with the depth of the seam, i. e. the 
lowest bench of coal of any typical seam, other things being 
equal, ought to be lower in volatile matter and higher in fixed 
carbon than the uppermost bench ; or that there is an apparent 
