1864.
HIND GLACIAL DRIFT.
12:
§ 4. Beaches and Terraces.
In connexion with this driftless area,
the beaches and terraces which form so
distinguishing a feature in North Ame-
rica acquire particular interest.
Confining myself to those terraces
which have come under my own obser-
vation, I shall notice first the vast bank
of sand, 55 miles west of Lake Superior,
commonly called the Great Dog Por-
tage*. The altitude of the summit of
this terrace is 835 feet above Lake Su-
perior, more than 800 feet above Lake
Michigan, and 1435 feet above the sea.
120 miles west of Lake Winnipeg the
successive steps or terraces of the
Riding and Duck Mountains rise in
well-defined succession on the south
and south-western slopes

but on the
north-east and north sides they pre-
sent a precipitous escarpment more
than 900 feet in altitude, or 1000 feet
above Lake Winnipeg, or 1600 feet
above the sea

while Lake Traverse,
which sends water during floods to the
Red River of the north as well as to
the Mississippi, is only 966 feet above
the same level; and from 10 to 15 miles
west of Lake Traverse and Big Stone
Lake (966 feet above the sea) is the
abrupt escarpment of the Coteaux des
Prairies, whose summit is 1000 feet
above them.
Illustrations of a precipitous escarp-
ment on one face, with gentle sloping-
plateaux separated by terraces on the
other side, might be greatly multiplied;
they are indeed the common feature in
the scenery of the basin of Lake Win-
nipeg, west of that lake

and, with a
single known exception, mentioned by
Dr. Hector f , the precipitous escarp-
ment faces the north-east or the north,
and the terraces and plateaux the
"«  v
^ 'O w

For a description of the Great Dog Portage, see 'Narrative of Canadian
Exploring Expeditions of 1857 and 1858.' Also Reports on the North-west Ter-
ritory, 1859. By the Author.
t The Cypres Hills, Quart. Journ. Geol. Soc. vol. xvii. p.