Evening star., 1936-12-19

The billions Of tons of rock which now
constitute the Blue Ridge Mountains and
the Valley of Virginia were transported
northwestward during 300,000,000 years
of geologic time from an hypothetical
highland which now probably is partially
covered by the Atlantic Ocean.
Such is the picture reconstructed by
Charles Butts. geologiSt OF the United
States National Museum. after many
years devoted to the study of Virginias
geological history. Mr.. Butts reported
his findings at recent meeting OF the
Virginia Academy of Sciences.
The story begins approximately half
billion years ago, at the very dawn OF
life on earth so far as it can be known
from the fossil record. At that time the
area covered by much Of the eastern
United States was low, fiat land. mostly
of granite rock and utterly barren. 1t
still was long time before vegetation
would start to cover the earth.
About this time something started to
happen on a titanic scale. A vast area
of this land began to sink. The axis OF
this sinking can be located roughly to-
day as starting in the northwest high
lands OF Scotland. extending across the
Atlantic, and running through New
foundland, Quebec, the Green Mountains
Of Vermont, the Blue Ridge of Virginia
and thence probably southwestward into
Arkansas and Oklahoma. The subsistence
presumably extended to equal distances
on each side of this axis.
With this subsistence the land was
pushed up-probably to some extent on
each side, although the chief uplift seems
to have been on the eastward. Sea waters
rushed into the trough, as is evidenced
by the fossils Of very ancient marine
fauna. 1t was, however, very shallow
embayment, Mr.. Butts believes. Erosion
started from the higher lands, filling this
shallow trough. 1t continued to sink
and the eroded material continued to
fill it up. Probably there were islands in
the embayment There are still rem
nants of the original granite base left
which in some way escaped subsistence.
The most notable of these, Mr. Butts
points out, is the st. Francois Mountain
range, in Southeastern Missouri. The
granite base also has been struck by
deep wells near Dayton. Ohio, and In
Eastern Kansas.
Altogether Mr. Butts estimates from
extensive measurements. in the present
area of the Valley of Virginia alone
total Of approximately 100000 cubic
miles of material was deposited. All the
time the subsidence was continuing.
There are now 1920 fee. Of deposited
rock-a little more than three miles, be-
tween the present floor OF the valley and
the ancient granite basement.
The process was extremely slow. AT
the present rate of discharge the Mis-
sissippi River would deposit 10000 cubic
miles of the material in about 1,200, 600
years and the Ganges in less than half
that time. This was lazy old earth
through the vast stretch Of paleozoic time
and the slow rivers loafed at their titanic
job of mountain moving.
The question then arises as to the d.
rection from which the sediment came.
Theoretically it might have flowed in
from both east and west Of the subsidized
area in approximately equal amounts.
The process. however, was very compli-
Gated, Mr.. Butts points out. and the vari-
Gus elements Of the geological picture
make this hypothesis impossible. At