Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1892-02-06
AN INTERESTING LECTURE.

John ID. shafer Reads Paper Before the
Academy of Science and Arts on the
Geology of the Vicinity of fittsburg-
Features of the Discourse.
John d. Shafer read paper before the
Academy of Science and Art last evening
on the geology of the vicinity of Pittsburg.
He said: 81 propose to present sketch oi
the geology of the vicinity of Pittsburg not
from professional, but personal point OF
view. The water taken up by the sun is
clean, but as soon as it falls TO the earth it
begins to dissolve the materials and
when by force of gravity formed into a
body begins to move mechanically
and always toward lower level,
and in doing so carries a load which 1t taxes
from the land. The obvious result of this
is the destruction of the land and its reduc-
tion to the sea level. This region is COM
posed of hills and valleys If we were to
strip of The loose earth we could see that
the hills are not thrown up, but that the
valleys have been dug out. If we take any
particular stratum, for example the coal
vein, we find the same LAYERS or strata above
and below il in the same relative position
wherever it is fonnd. The layers Of rock
are called carboniferous because they are
interspersed with vegetable origin called
Goals
"The carboniferous rocks, which contain
the valuable Goals that make Pittsburg
what it is begins at the thick sandstone III
the Allegheny Mountains northeast of us.
As we approach Pittsburg this rock grad
ually slopes down and is about GOO feet
under where we stand. Above this lies a
series of rocks about $50 feet thick
called the lower production coal meas
ures. In this thickness there
are about five workable coal beds.
At different places and about 100 feet above
the Piedmont sandstone is thick lime
stone called ferriferous, from which Is
mined the limestone used by blast furnaces
here. Over the lower coal measures lies
series of rocks called the lower barrens, be-
cause it has no workable coal beds and in
that sense is non-productive. The lower
barrens form the surface of almost all of
Allegheny county north of the Ohio and
Allegheny rivers. The Mahoning sand
stone is in two layers, with some limestone
and shale between; it NAV be seen in this
vicinity, and is the best building stone to
be found hereabouts. Immediately over
this is limestone about three feet thick,
which is geologically important.
''In the barrens it is hard to tell where
you are or what is above and below you,
owing to the variable character of the strata,
but this Limestone, which is a continuous
sheet over the country, is called the green
crinoidal, which is very hard, and
wherever found you know you are
half way between the Mahoning
sandstone and the Pittsburg coal.
Above this is a mass Of shale,
streaked with yellow and. red. Near the
top it contains an impure limestone COM
posed of hard Jumps containing iron. This
rock can be seen in Coal Hill. A few feet
further up you will come to the nodula
limestone Next sandstone known as the
Morgantown, of which Boyd's Hill is COM
posed. Further up the hill you meet
two limestones which cross the road and a
third at the bend; this is but a few feet
below the Pittsburg coal. The Pittsburg
coal bed is commercially and geologically
the most important of all the strata for
many hundreds of feet above and below it.