Irving, R.D., 1888, On the classification of the early Cambrian and pre-Cambrian formations: U.S. Geological Survey 7th Annual Report, p. 371-454. Authors Irving, R.D. Publication Date 1888 Citation U.S. Geological Survey 7th Annual Report, p. 371-454. Keywords Proterozoic Cambrian Stratigraphy More Keywords Proterozoic, Cambrian, Stratigraphy, AzGeoBib RefNum 4834