Along this leg of the excursion we follow an ancient valley of the pre-glacial Missouri River.  The valley is broad and flat; and is occupied today only by several minor streams.  Along the way northwards, a short distance north of Big Sandy, we pass on the left side the pre-glacial channel of the Marias River.  The valley wasn't very deep, so what can be seen today is just a broad depression on the landscape.  There are several small, shallow lakes there, such as Lonesome Lake.  The evidence of the pre-glacial Marias Valley here has been nearly erased by ice moving across its channel.  Pre-glacial valleys that were occupied by long tongues of southward flowing icesuch as the one in which we are travellingare usually better preserved.
See detail map
Highway 87 north to Havre, follows a broad level valley, and crosses only several very small streams.  As we enter the city of Havre, we descend again from the pre-glacial valley, in which we have been travelling. into another relatively young, narrow valley.  Here, as at Fort Benton, one can discern the remnants of a broad valley above the town.  The Milk River has cut its channel into the old flood plain, so the city lies mostly below the old valley.  This is best seen from north of the city, along Wildhorse Trail Road [Site 12], where we see that the old valley was constrained by the Bearpaw Mountains and hills to the south.  In the photograph the old valley begins beyond the wheat fields in the foreground.  Then is a bench about a mile across, followed by a descent into the present-day Milk River Valley and the city of Havre.  The valley is about 200 feet deep, but doesn't show very well here because trees have been planted on the sides.
A side trip northwest of Havre would reveal that the Milk River now
flows through broken badland country near the U.S.-Canada border; and
the valley from there to Havre is quite young, with only a narrow
floodplain along the bottom.  (Part of the valley has been filled
by a reservoir impounded by Fresno Dam.)  In fact the river has
apparently cut through a rise extending southwestward from the Cypress
Hills toward the Rockies.  What has happened becomes quite clear
on topographic maps.  Originally the Milk River flowed
northeastward from the Rocky Mountains; and turned abruptly northward
at the Cypress Hills to join the South Saskatchewan, at roughly the
location of Medicine Hat, Alberta.  When the glaciers began to
recede, and the rivers began to flow again, the Milk River was still
blocked by ice, and had to cut a new channel toward the southeast.
When it reached the old Missouri Valley, it found a ready-made valley,
in which it has continued to flow.
About 10 km east of Havre, on U.S. Highway 2, the valley broadens,
where the grade of the Milk River has adjusted to the old valley.
From the village of Lohman eastward the valley is broad and flat, with gentle
hills bordering it on each side.  In many places the valley is 5
or more miles (8 km) wide; clearly too large to have been excavated by
the Milk River.  The country here was all smoothed by the
glaciers; and some fine moraines and kettle lakes can be found to the
north, near the U.S. Canada border.
|Start, Big Sandy||0.0||0.0||N48° 16.59'||W110° 7.02'|
|Old Marias Valley Overlook
just a dip in the western horizon
|14.7||9.1||N48° 17.49'||W110° 1.79'|
|Havre, Wildhorse Trail (left turn)||57.1||35.5||N48° 33.18'||W109° 40.32'|
|  Milk River Valley Overlook||60.7||37.7||N48° 34.79'||W109° 41.45'|
|Return to Havre||64.3||40.0||N48° 33.18'||W109° 40.32'|
Next, we can either travel west and north
to explore the old valley of the Milk River,
travel east to see the new valley taken over by the Milk River from the pre-glacial Missouri.
Photographs by G.  Davidson