93

geologists studying the Mesozoic that many correlations based on litho- logical resemblances alone have been unreliable, and that they have been revised when faunal evidence has become available.

__ Three and possibly four macrofaunas are known, and furnish faunal evidence for correlation. The three well-defined faunas are, in descending order:

Neogastroplites fauna Gastroplites fauna Lemuroceras or Beudanticeras affine fauna

The Lemuroceras fauna, as recorded in previous paragraphs, carries species of the genus Lemuroceras, and Beudanticeras affine (Whiteaves), and some pelecypods. The Gastroplites fauna includes species of Gastroplites and Inoceramus, and some starfish. The Neogastroplites fauna has species of Neogastroplites, Posidonomya, and Oxytoma. It is possible, but far from proved, that a fourth ammonoid zone lies between the Gastroplites and Neogastroplites zones. It contains crushed specimens of an ammonoid difficult to identify generically. Specimens collected by McConnell on Liard River were described by Whiteaves (1892) and given the name of Placenticeras liardense, and may represent a younger ammonoid genus than Gastroplites.

The Lemuroceras fauna is found in the Moosebar and Gates formations on Peace River, and permits a faunal correlation of these strata with a lower part of the Buckinghorse formation on Sikanni Chief River. The Gastroplites fauna has been reported from the upper part of the Commotion formation on Pine River, and makes possible a correlation of that part with a lower part of the Hasler formation on Peace River and an upper part of the Scatter formation and lower part of the Lépine on Liard River. The Neogastroplites or Posidonomya nahwisi fauna in the Goodrich formation on Pine and Peace Rivers correlates that formation with the lower and sandstone-bearing part of the Sikanni formation on Sikanni Chief River; the middle sandstone in Tetsa River Valley; a part of the ‘fissile shale’ on Petitot River; and shales high in the ‘Shaftesbury’ formation east of Cache Creek on Peace River.

The correlations, considered in the foregoing paragraph and based on faunal evidence, afford a strong supporting framework for the remaining correlations, which, unfortunately, must rest on the weaker lithological evidence. Because of similar lithology and similar stratigraphic position the Moosebar shale on Pine River is correlated with the Moosebar on Peace River. The claim made by students of the Pine River section that the Commotion formation on Pine River is equivalent to the Gates plus a lower part of the Hasler formation on Peace River is a reasonable one, for it has already been demonstrated that faunal evidence supports a correla- tion of the upper part of the Commotion with the lower part of the Hasler formation, and the evidence of similar lithology supports a correlation of the lower part of the Commotion formation with the Gates.

On lithological evidence, Allan and Stelck (1940) compare the Moosebar ’ shales and Gates sandstone with similar shales and sandstones in the No. 1 Guardian well near Bonanza, Alberta, just east of the area included in this

report.