Dictionary.net

• A subdivision at the base of the cretaceous formation in Western North America; - so named from the region where the strata were first studied.

2010 - New Age Dictionary Database
By Oddity Software

• A subdivision at the base of the cretaceous formation in Western North America; - so named from the region where the strata were first studied.

1913 - Webster's Revised Unabridged Dictionary
By Noah Webster.