Summary of Conspicuous Geologic Features of the Lower Tertiary Sequence
Published:January 01, 1959
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.
Figures & Tables
Lower Tertiary Biostratigraphy of the California Coast Ranges
As a result of field work carried on in 1947 a sequence of foraminiferal samples were collected in 2,300 feet of Lower Tertiary mudstones, siltstones, and interbedded shales and sandstones in the vicinity of Media Agua Creek, in the Temblor Range on the west side of the San Joaquin Valley.
Foraminiferal samples from another less comprehensive sequence of Lower Tertiary strata were collected during the years 1947, 1948, and 1949 in the region of Devils Den.
The prepared samples were studied during the years 1947–1952 in the Department of Paleontology at the University of California under the direction of Dr. Robert M. Kleinpell. Subsequent work both in the field and laboratory has been directed toward obtaining as complete and chronologically diagnostic a faunal sequence throughout the Lower Tertiary in the California province as possible.
Preliminary results of certain phases of the investigation have been presented from time to time at meetings of the Pacific Section of the American Association of Petroleum Geologists, San Joaquin Valley Geological Society, Cordilleran Section of the Geological Society of America, and the Northwest Geological Society (Mallory and Boyd, 1949; Mallory, 1953a, 1953b, 1954a, 1954b). This paper attempts a synthesis and revision of these reports and their conclusions, and the incorporation of many new data.
The majority of species known to be important in the Paleogene foraminiferal faunas are figured and their stratigraphic distribution in the California province is noted. In addition, an attempt has been made to draw any inferences from all kinds of fossil