When the rock masses gradually rose as mountains above the retreating sea, they were weathered and eroded into a landscape similar to that of the Rocky Mountains today.
(the rock masses; gradually rose; as mountains above the retreating sea) (they; were weathered; T:When the rock masses gradually rose as mountains above the retreating sea) (they; eroded; T:When the rock masses gradually rose as mountains above the retreating sea)
the rock masses they they
gradually rose were weathered eroded
as mountains above the retreating sea
T:When the rock masses gradually rose as mountains above the retreating sea
T:When the rock masses gradually rose as mountains above the retreating sea