Leptopecten alockamanensis (Weaver, 1912)
WEAVER, C. E. 1912. A preliminary report on the Tertiary Paleontology of Western Washington. Bulletin of the Washington Geological Survey, 12: 1-80, pls. 1-15. [p. 58, pl. 13, fig. 115]
1912 Pecten alockamanensis Weaver, 1912
C. E. Weaver, 1912, plate 13.
|
«Description.— Shell small, much higher than long, equivalve, equilateral; sides straight and sloping regularly at an angle of 50° from the beak; base regularly rounded; left valve has 13 or 14 equally rounded ribs which are not sulcated; interspaces are flat-bottomed and slightly wider than the radiating ribs. Surface ornamented with fine incremental lines; anterior ear about one-third longer than posterior; byssal area moderately deep; posterior ear truncated and both ornamented by fine concentric lines.
Dimensions.— Longitude 18 mill.; altitude 24 mm.; diameter 3 mm. Occurrence.— Common at Loc. No. 54 (University of Washington Palaeontological Collection) near the head of Alockaman River, Cowlitz. County, in Sec. 2, T. 9 N., R. 5 W. Horizon.— Near base of Wahkiakum formation, Lower Miocene.» CHARLES EDWIN WEAVER, 1912
|
«Newportian Stage
Shallow-water pectinids are most abundant in provincial upper lower and middle Miocene rocks. The most commonly occurring species is Patinopecten propatulus (Conrad). This pectinid (PI. 3, fig. 1) ranges from western Washington (Wolfe and McKee, 1972) to the San Joaquin basin of central California (Adegoke, 1969). Another pectinid restricted to this stage is Leptopecten andersoni (Arnold). This species (PI. 2, fig. 2) ranges from the Grays Harbor basin of western Washington (Etherington, 1931; as Pecten andersoni clemonensis) to the Los Angeles basin, southern California (Vedder in Headlee and others, 1970) in the Newportian and the coeval "Temblor" Stage (Addicott, 1972) of California. Other species from the Newportian Stage include the giant pectinid Patinopecten oregonensis cancellosus Moore (PI. 2, fig. 7) from unnamed Miocene rocks dredged from Coos Bay, southwestern Oregon, and Leptopecten alockmanensis (Weaver) from the Astoria (?) Formation of southwestern Washington. Both of these distinctive pectinids, however, are known only from the type localities and are therefore not particularly useful in provincial biochronology.»
ADDICOT, W. O. 1981. Significance of pectinids in Tertiary biochronology of the Pacific Northwest. Geological Society of America, Special Papers, 184: 17-38, pls. 1-4. [p. 23, 24]
|