The continental ice-sheet is the cause of the wide-stretching,
gently rolling to rough drift plain with its numerous lakes and
imperfect drainage which occupies nearly two-thirds of the state.
Its effects are everywhere apparent and unmistakable. Before
its advent the area was undoubtedly more uneven than at present,
since it was an old land surface which had been roughened by the
long continued erosion of streams. The ice-sheet modified all this
and tended to level up the region by wearing down the hills and
ridges and filling the valleys with debris. Upon its retreat' there
was left the heavy mantle of drift which conceals from view the
old preglacial surface. It is this drift which forms the rolling,
and in places rough, plain stretching westward from the Red River
Valley clear to the Montana line north of the Missouri, and ex-
tending fifty miles or more west and south of that river.
The broad, flat plain knmvn as the. Red River Valley was also
formed through the agency of the ice-sheet. The valley consti-



THE BOTTINEAU GAS FIELD



BY



JOHN G. BARRY



STATE OF NORTH DAKOTA



THE BOTTINEAU GAS FIELl

BY JOHN G. BARRY.
