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AAPG Bulletin


Volume: 15 (1931)

Issue: 10. (October)

First Page: 1296

Last Page: 1296

Title: United States Geological Survey Bulletin: ERRATUM


W. C. Mendenhall, acting director of the U. S. Geological Survey, desires to bring to the attention of Association members an error in the definition of the Moreno formation as published in the Survey Bulletin 826, the lexicon of California stratigraphy. The following copy of a correction slip to be inserted opposite page 52 in Bulletin 826 will be sent to anyone, especially anyone who has already received that bulletin, on application to the Survey at Washington, D. C.


Moreno formation.

Upper Cretaceous: Southern California (Diablo Range).

R. Anderson and R. W. Pack, 1915 (U. S. Geol. Survey Bull. 603):
Upper formation of Chico group. Rests conformably on Panoche formation, the lower formation of Chico group, and is unconformably overlain by Cantua sandstone member of Martinez (?) formation. In the southern area it consists of foraminiferal and diatomaceous maroon and chocolate-colored shale and dark clay shale, with some interbedded sandstone, and has a maximum thickness of about 1,600 to 1,800 feet. In the northern area it contains less of the shale of truly organic origin and more clay shale and sandstone and is unconformably overlain by Tejon formation. Typically exposed in Moreno Gulch, on east flank of Panoche Hills, where it is 1,700 to 2,000 feet thick and composed predominantly of thin-bedded, rather brittle brownish and lavender-colored shales that weather into small bits and lakes. In lower part of formation are numerous beds of sandstone, locally containing poorly developed concretions and in general similar to the sandstone of Panoche formation. The upper half of formation is more nearly pure shale and contains a greater proportion of material of organic origin. Calcareous shale, limestone nodules, and layers of semiporcelaneous siliceous shale occur locally, and near top of formation is a zone of white platy diatomaceous shale about 200 feet thick, which is traceable most of way along face of Panoche Hills, Fresno County. Line between Moreno and Panoche formations is arbitrarily drawn at horizon where the sandstone beds that form the steep eastern slope of Panoche Hills dip beneath the predominantly shaly beds.

(To face p. 52, U. S. Geological Survey Bulletin 826)

End_of_Article - Last_Page 1296------------

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