The glaciers wore away the sides of some of these canyons, forming broad, U -shaped valleys.
(The glaciers; wore away; the sides of some of these canyons) Context(The glaciers wore away,List([0, 22))):(The glaciers; wore away the sides of some of these canyons forming; broad, U -shaped valleys)
The glaciers wore away,List([0, 22))
The glaciers The glaciers
wore away wore away the sides of some of these canyons forming
the sides of some of these canyons
broad, U -shaped valleys