Beginning about 4 million years ago, the Broadwater Formation was deposited by a river ancestral to the South Platte River, which drained parts of the Southern Rocky Mountains of north-central Colorado and parts of the adjacent Great Plains.
(the Broadwater Formation; was deposited; by a river ancestral to the South Platte River; T:Beginning about 4 million years ago) (the South Platte River; drained; parts of the Southern Rocky Mountains of north-central Colorado and parts of the adjacent Great Plains)
the Broadwater Formation the South Platte River
was deposited drained
by a river ancestral to the South Platte River T:Beginning about 4 million years ago
parts of the Southern Rocky Mountains of north-central Colorado and parts of the adjacent Great Plains