Before the Glen Canyon Dam was constructed, seasonally high riverflows carried large sediment deposits through the Glen and the Grand canyons and scoured away or buried most vegetation from the river corridor below the 100,000 to 125,000 cubic feet per second river stage elevation.
(the Glen Canyon Dam; was constructed; ) (seasonally high riverflows; carried; large sediment deposits; through the Glen and the Grand canyons; T:Before the Glen Canyon Dam was constructed) (seasonally high riverflows; scoured; away; T:Before the Glen Canyon Dam was constructed)
the Glen Canyon Dam seasonally high riverflows seasonally high riverflows
was constructed carried scoured
large sediment deposits through the Glen and the Grand canyons T:Before the Glen Canyon Dam was constructed
away T:Before the Glen Canyon Dam was constructed