The commonwealth. (Greenwood, Miss.) 1896-1923, 1909-10-01

While these general facts concern
ing changes in land level in ancient
geological times beyond all question
are very impressive, less attention
than they merit has been given to
the facts showing hat corresponding
changes are still going on, and have
produced striking results within re-
cent times, and point to interesting
conclusions with reference to the flu
ture. In connection with the glacial
period, which is the most recent of all
n geological epochs, these changes
of level are very evident, and connect
themselves with the early history of
mankind. At the close of the tertiary
period, which eliminated in the
glacial era, the central and northern
part of North America stood at a
level of 1900 or 5000 feet above that
it at present occupies. This is proved
by the existence of innumerable chan
nels now deeply buried by glacial de-
bris, or extending out into the ocean
across the shallow, submerged shelf
of the continent both upon the Allan
tic and Pacific coasts. In Illinois, in
Ohio and in central New York these
buried channels are found down be-
low sea level, showing hat the land
must have been very much elevated
to allow the streams which crossed
these rocky gorges to make their way
to the sea from these distant inland
points. The cities of Cleveland, O.,
and Syracuse, N. Y, are built over
such buried gorges. The Delaware,
the Hudson n the ST. Lawrence
rivers then emptied into the sea, run
ming through deep gorges or canyons.
which crossed a level coastal plain.
The fiords of Greenland and of Nor
way and of the Pacific coast of North
America bear similar testimony, since
they probably, in most cases, mark
the lines of ancient rivers which
coursed through them to the sea when
the land was sc much elevated that
what are now the bottoms of these
channels were occupied by rushing
mountain torrents. In short, these
fiords are drowned river valleys.
But at the close of the glacial period
the land levels in all this northern
region were much lower than at the
present time. On the southern coast
Of New England sea beaches were
thrown up about fifty feet higher than
those which are formed now. Along
the southern shore of Maine the land
had sunk so much that sea shells are
found in clay deposits $50 feet above
the present sea level. The Champlain
and st. Lawrence valley was so much
depressed that whales sported in salt
water over the site of Middlebury col
lege, Vermont, and seals ventured into
an arm of the e extending far up
into the Ottawa river, while at Mon.
treal modern sea shells are found 500
feet above present tide water upon
the top of the mountain which gives
the city it's name. Going farther
north the indications are that upon
the shores of the Arctic sea post.
glacial subsistence amounted to 1,OO0
feet Everywhere across the continent
there is cumulative evidence that this
po~st-glacial subsistence was as exten.
sive as the glaciated region, and that
it increased in amount from south to
north. This is a very important con
~sideration to be kept in mind in work
ing u glacial and post-glacial prob
lens. This d%ifferential northerly de
preston at the close of the glacial
period caused the great lakes to flow
at first into the Ottawa river across
Lake Nippissing over the site Of
North bay into the hathaway river
and so into the Ottawa along the line
through which the Canadian govern
ment is talking of building a shiI
canal, and which is already utilized by
the Canadian Pacific railroad. This
pass is now less than 100 feet above
the level of the lakes.
Copyright by Joseph B. Bowles.)