St. Paul daily globe., 1896-02-08
LAKE AGASSIZ.
The Great Glacial Lake of North
America,

The Great Glacial Lake of North
America.
The Northwestern Weather and Crops
a valuable journal of Minneapolis, con-
tains a printed copy of an address on
the above-named subject by Prof.
Warren Upham, delivered before the
Minnesota Historical society, Jan q.
1895. 1t gives a very elaborate and in
structive description of that ancient
lake, named Agassiz by modern scien-
lists, in honor of that distinguished
naturalist. He says: 'Leveling along
the highest beach shows that Lake
| AgassiZ, in it's earliest and highest
stage, was nearly 200 feet deep above
| Moorhead and Fargo; a little more
than 300 feet deep above Grand Forks
| and Crookston; about $50 feet above
| Pembina, ST. Vincent and Emerson,
and about 500 and 800 feet, respectively,
! above Lakes Manitoba and Winnipeg.
| The length of Lake Agassiz is estimat-
| ed to have been nearly 700 miles, and
it's area not less than 10000 square
miles, exceeding the combined areas of
the five great lakes tributary to the
| st. Lawrence.
He shows that the glacial drift in the
great basin, known as the Red river
valley, is so thick that no exposures of
the underlying rocks have been found;
that the depth ranges from 100 to 250
| feet; that this vast plain, once the bed
of the most magnificent lake on the
continent, extended from 25 to so
miles wide and 300 miles or more long
north to Lake Winnipeg, which fingers
yet as fraction Of departed greatness.
The professor maintains that the basin
of the Minnesota river was anciently
cut by the outflow of the lake, as the
ice dam melted near it's southern
boundary at the point now known as
| Browns valley where the writer of
this resides. Prof. Upham says: SAT
first it's flow was upon the nearly level
undulating surface of the drift LOO
| to LBS feet above the sea, at the west
side of Traverse and Big Stone coun-
ties; but in process of time this cut
a channel here called Browns valley,
100 to $50 feet deep and about mile
wide, the highest point of which, on
the present water divide between the
Mississippi and Nelson river basins, is
975 feet above the sea level. From this
outlet the Red river valley plain ex-
tends 315 miles north to Lake Winni-
peg, which is 10 feet above the sea.
Along this entire distance there is
very uniform continuous descent of a
little less than one foot per mile
An interesting feature of the Browns
valley, called the great divide" is the
depth of the drift here. In digging the
artesian well several years ago, we
went down through an almost con-
tinuous bed Of blue clay that grew
blacker and blacker as we descended,
and passed below the deposit at depth
OF 400 feet below the valley level or
about 600 feet below the prairie level
above the bluffs. 1t is we'll known that
clay is resultant of the grinding of the
rocks. We have no positive data by
which to determine how many centuries
must have elapsed in digging out this
immense tunnel and filling it to the
brim with the 'stOne meal" Prof. Up
ham, however, gives us clew:
1.-The entire duration of Lake Agas-
siz. estimated from the amount of it's
. wave action in erosion and in the accu-
mutation of beach gravel and sand
j, appears to have been only about ], ,00O
years, and the time of it's existence is
! thought to have been somewhere from
5000 to 10000 years ago."
On the west side of this great di-
vide,'' hugging the bluffs, that are about
$50 feet high, is plainly to be seen the
bed of the ancient river formed when
away. At that period the now known
. one and the same, constituting the
great continental water belt between
the waters of Hudson's bay and the
!. Gulf of Mexico. The mountains OF
: movable ice, the melting away, the pill
= ing in of the drift" the growing anC
9 decay Of vegetations, perhaps great for
ests long ago wasted, prepared the way
. fol the fertile plain now occupied by
S busy populations. j. o. Barrett,
. Secretary State Forestry Association.