The force of these moving continental glaciers was great enough to carve out the Great Lakes and create the hills and valleys of central and southern Canada.
(The force of these moving continental glaciers; was; great enough to carve out the Great Lakes and create the hills and valleys of central and southern Canada) (The force of these moving continental glaciers; to create; the hills and valleys of central and southern Canada)
The force of these moving continental glaciers The force of these moving continental glaciers
was to create
great enough to carve out the Great Lakes and create the hills and valleys of central and southern Canada
the hills and valleys of central and southern Canada