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New allostratigraphic correlations in west-central Alberta show that flooding surfaces in the Sunkay and basal Vimy members of the Blackstone Formation can be traced eastward from Burnt Timber Creek for >500 km to western Saskatchewan, and for 350 km northward into the Dunvegan and Kaskapau formations. At Burnt Timber Creek, a Miliammina manitobensis microfauna in the lowest 1 m of the Sunkay Member indicates equivalence to the Westgate Formation, and an overlying 70 cm conglomerate is correlative with the Fish Scales Formation. Overlying mudstones contain foraminifera of the Verneuilinoides perplexus Zone, indicative of the middle Cenomanian Belle Fourche Formation. The base of the Second White Specks Formation, as currently defined in core in eastern Alberta, equates in outcrop with the lower part of the Sunkay, rather than the base of the Vimy Member as previously thought. The base of the Second White Specks Formation should be placed about 35 m higher in the stratotype core. A bentonite located 9.3 m above the base of the Sunkay Member at Burnt Timber Creek lies near the highest occurrence of Evolutinella sp. aff. E. apricarius, indicating proximity to the "X" bentonite, recognized across the prairies and traceable north into allomember C of the Dunvegan alloformation. A thick bentonite 93.2 m above the base of the Burnt Timber Creek section lies 4 m above the base of the Vimy Member; this bentonite, traceable from northern British Columbia to New Mexico, lies a few metres below the Cenomanian–Turonian boundary and is here formally named the Bighorn River Bentonite.

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ABSTRACT. The benthic foraminiferal succession from the Beaufort-Mackenzie Basin of arctic Canada reflects many of the major oceanographic and climatic events of the Tertiary. The Paleocene-Eocene epochs are characterized by restricted marine circulation and pronounced foraminiferal endemism. Paleogeographic reconstruction illustrates that the Paleocene-Eocene Arctic Ocean was markedly different from its modem counterpart and it is thus referred to as the "Arctic Gulf." Marine connections between the Arctic and Atlantic oceans were broadened and deepened during the Oligocene. The Arctic Gulf thus evolved into a modern Arctic Ocean configuration by sea floor spreading in the Greenland-Norwegian Sea.The Oligocene index, llrrrilina akatica Andreae, appeared in the arctic regions concurrent with increased circulation between the North Atlantic and Arctic oceans. In the Beaufort-Mackenzie subsurface, llrrrilina akatica has proven to be a widespread and reliable zonal index. In outcrop, it is known from only one locality, the Nuwok Member of the Sagavanirktok Formation on Carter Creek, Alaska.During the Miocene, increased circulation between the Arctic and Atlantic oceans was further established, and a moderate warming trend developed after a cool early Oligocene episode. The foraminifer Asterigerina staeschei (Franke) is an abundant and widespread marker of this phase of arctic marine history. Asterigerina staeschei became extinct in the middle Miocene in both the arctic and North Atlantic regions. In the Beaufort-Mackenzie Basin, many associated species ranged through into the late Miocene but disappear abruptly at the terminal Miocene unconformity. Major faunal and depositional sequence changes mark this as one of the most significant events in arctic Tertiary history, and the unconformity itself was caused by a widespread relative drop in sea level.A major faunal turnover in the Pliocene is characterized by Cibicides grossus ten Dam and Reinhold, which first appeared in the early Pliocene but became extinct through the North Atlantic and arctic regions at approximately 2.4 Ma, closely approximating the climatic deterioration and initiation of continental glaciation in the late Pliocene. Cibicidesgrossus has a widespread distribution in arctic North America, occurring in the subsurface of the Beaufort-Mackenzie Basin and in outcrops of the marine tongue of the Beaufort Formation on Meighen Island, in unnamed strata on White Point of northwest Ellesmere Island, on eastern Baffin Island, and on eastern and northern Greenland.

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