The Cretaceous strata exposed in the Ono and Chanchelulla Peak quadrangles, Calif., predominantly siltstone, mudstone, and sandstone, are placed in a single formation, the Budden Canyon Formation, which is divided into seven members. Their thickness increases from 7,400 feet in northern Ono quadrangle to 22,000 feet in southern Ono and Chanchelulla Peak quadrangles. They range in age from Hauterivian to Turonian. The term Ono Formation has been abandoned since its retention would require major changes in the original definition.

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