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Since the research undertaken for this discussion of Lower Tertiary stages was primarily undertaken with a view toward discovering a complete faunal sequence throughout the Lower Tertiary and toward establishing the range of Foraminifera, only the broadest and most conspicuous features of a geologic nature which were found to be associated with the faunas are discussed. The areal geological, distributional, structural, and petrological aspects of the various stages were not studied in detail except as necessary to establish control. These features deserve detailed study, but only the most salient of them will be discussed here as to their possible significance to the geologic history of the California province during Early Tertiary time.

Angular unconformities indicating orogenic folding are present locally throughout the California province at the Cretaceous-Ynezian boundary. Other angular unconformities are common at the base of the Ulatisian Stage, and occasionally in the Narizian (see Reed, 1933, pp. 112–114, for further discussion).

Transgressive marine sedimentation is indicated by overlap primarily in the Ynezian, Penutian, and Ulatisian Stages. The upper Ulatisian, in particular, is widely transgressive. The Bulitian seems to be regressive between the Ynezian and Penutian transgressions, and the Narizian seems also to be regressive, at least locally. Relief seems to have been the greatest at the onset of Ynezian time, as indicated by the frequent coarse clastics of the Martinez, Simi conglomerate, and other formations. The Narizian (locally) shows great relief with deep bathyal to abyssal faunas developed along the west side of the San Joaquin Valley.

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