FORAMINIFERA FROM THE CLALLAM FORMATION
The known foraminiferal fauna of the Clallam formation consists of 11 species (table 4) collected from three localities (f11891, f11892, f11893) in the northwest part of the mapped area.
TABLE 4.Foraminifera from the Clallam
Although the fauna is small, it nevertheless is indicative of age. Nonion costiferum makes its lowest occurrence within the area at the base of the Clallam formation. According to Kleinpell (1938, p. 116), N. costiferum makes its first occurrence in the Saucesian stage of California. This statement is substantiated by observations of the writer in Oregon and in southwestern Washington. In southwestern Washington it makes its lowest occurrence in the Epistominella parva zone (Rau, 1958), which occurs largely in strata mapped as the lower part of the Astoria (?) formation (Snavely and others, 1958; Pease and Hoover, 1957). In western Oregon its lowest known occurrence is near the base of the Nye mudstone in the Yaquina Bay area. The foraminiferal faunas of both the lower part of the Astoria (?) formation and the Nye mudstone are considered to be of Saucesian age by the writer. Both Bolivina advena Cushman and Valvulineria cf. V. depressa Cushman support a Saucesian age even though they occur in small numbers in the Clallam formation.
The upper age limit of the known foraminiferal fauna of the Clallam formation is not as strongly indicated. Anomalina californiensis makes a rare occurrence at one locality. This species is little known above the lower part of the Saucesian stage. A Saucesian age for at least the lower part of the Clallam formation is further suggested by stratigraphic evidence because in places the Clallam formation rests conformably on Zemorrian age strata of the Twin River formation (Gower, 1960). Foraminifera were not collected from the uppermost part of the Clallam formation and therefore the age of that part of the formation was not determined on the basis of Foraminifera. The Saucesian stage of the standard west coast section (Weaver and others, 1944) is regarded as "Oligo-Miocene" in age.
The small foraminiferal fauna of the Clallam formation is also suggestive of the environment in which it lived, probably a shallow, cool, and somewhat sheltered sea. Nonion costiferum is common in samples from the three localities. Kleinpell (1938, p. 15; and table 1) inferred that this species is common in neritic waters and in areas sheltered from current action. Furthermore, Kleinpell (1938, fig. 5) considered the genus Nonion to be a cool-temperate-water form. Elphidium cf. E. minutum is also common in the Clallam fauna. Species similar to it are almost always found at shallow depths (Phleger and Parker, 1951, pt. 2, p. 10). Eponides mansfieldi oregonensis occurred at all three Clallam localities. This species is similar to E. hannai, which Phleger and Parker (1951, pt. 1, p. 51) indicated is confined to depths of less than 100 meters in the northwest part of the Gulf of Mexico. Gyroidina orbicularis planata, which occurred at one locality in the Clallam formation, is the only conflicting evidence for a shallow depth, because records of this species are usually from greater depths. However, its known preference for cold water suggests cool-water conditions as suggested by Nonion. The remaining species from the Clallam formation occur too rarely, or their recorded environments are too varied, to be suggestive of the probable environment.
Last Updated: 28-Mar-2006