During this time, sediments eroded from the uplifting Rocky Mountains were being deposited in huge alluvial fans that formed the Great Plains .
(sediments; eroded; from the uplifting Rocky Mountains) (sediments eroded from the uplifting Rocky Mountains; were being deposited; in huge alluvial fans; T:During this time) (huge alluvial fans; formed; the Great Plains)
sediments sediments eroded from the uplifting Rocky Mountains huge alluvial fans
eroded were being deposited formed
from the uplifting Rocky Mountains
in huge alluvial fans T:During this time
the Great Plains