Abstract A study group of the Alberta Society of Petroleum Geologists proposed the following classification of Lower Cretaceous strata in the Peace River area of west-central Alberta: Fort St. John group Shaftesbury formation Peace River formation Paddy sandstone member Cadotte sandstone member Harmon shale member Spirit River formation Notikewin sandstone member Falher member Wilrich member Bluesky formation Bullhead group The Shaftesbury formation is a dark marine shale. The Peace River formation contains fairly distinct units consisting of the Paddy continental sandstone containing some coaly beds, the Cadotte glauconitic marine sandstone, and the Harmon dark marine shale. The Spirit River formation is a variable succession of sandstones and shales grouped into the Notikewin sandstone, the Falher sandstones, shales, siltstones, and thin coals, some beds suggesting deltaic origin, and the Wilrich dark shales with interbedded sandstones. The Bluesky formation consists of glauconitic sandstone grading down to dark shale. The Bullhead group is a variable succession of conglomerates, sandstones, shales, and coals.

Abstract In the light of recent exploratory drilling, some formation boundaries described in the previous paper are redefined and outcrops are correlated with the subsurface. The territory comprises 5,500 square miles of plains area which lies in west-central Alberta, 500 miles northwest of Edmonton. There are approximately 3,400 feet in the west to 2,400 feet in the east, of Upper Cretaceous beds called in ascending order, the upper Shaftesbury, Dunvegan, Kaskapau, Cardium, Wapiabi, and basal Member A of the Wapiti. Recent paleontological studies have shown that in the subject area the base of the Upper Cretaceous may be drawn at the top of the zone containing abundant fish remains which occur in the shales below the Dunvegan formation. The top of this zone is recognized in outcrop, and in subsurface it can be picked at a base line shift toward the left of the resistivity curve of an electric log. It also corresponds with a prominent “in-kick” on a gamma radio-activity log. It is herein suggested that the name “Upper Shaftesbury” formation be applied to the shales between the fish scale zone and the base of the Dunvegan. In this paper, the formational name Cardium is so used to embrace the Bad Heart sandstone.