The Queen Elizabeth Islands of the Canadian Arctic Archipelago are considered most favorable for petroleum exploration. The main structural feature is the Parry Island fold belt extending from west-central Melville Island east across Bathurst and Cornwallis Islands and thence northeasterly. The strata within the fold belt are a conformable sequence of Ordovician to Upper Devonian beds. The age of folding is placed as Hercynian. South of the Parry Island fold belt, the Ordovician--Upper Devonian succession is essentially a gentle north-dipping homocline broken by the northsouth-trending Boothia Arch on which movement occurred in late Silurian or early Devonian time (Caledonian). North of the fold belt, the Sverdrup Basin is a conformable sequence of Pennsylvanian to Tertia y strata. The sedimentary axis of the basin

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extends from northern Melville Island northeasterly through the Ringnes Islands to Axel Heiberg Island-- the deepest part of the basin. Tertiary tectonics produced north to northeasterly trending structures in the eastern part of the Sverdrup Basin. In the remaining part of the basin folding was less intense. Along the sedimentary axis of the basin are piercement domes and diapiric folds.

The Winter Harbour anticline was chosen as the location for the first well in the Arctic Islands because of its accessibility as well as favorable geology. In a normal season, ships could reach Winter Harbour from the east through Lancaster Sound. The structure is a large gentle fold on the southern side of the Parry Island fold belt. The primary objective was the Read Bay-Allen Bay reef carbonates of Silurian-Ordovician age.

Dome et al. Winter Harbour No. 1 was spudded September 10, 1961, and abandoned April 7, 1962, at depth of 12,543 feet. It drilled continuously throughout the winter without any serious difficulty. The section drilled consisted of an upper unit, 7,874 feet thick, of non-marine sandstone, siltstone and shale of Upper and Middle Devonian age. This was followed by 3,730 feet of Devonian-Silurian marine shale. The remaining 939 feet was Silurian and possibly Ordovician nonporous dolomite and anhydrite. The marine shale sequence represents, in part, the off-reef shale facies of the main objective, the Read Bay-Allen Bay carbonates. Although good reservoir beds were not encountered, the information obtained will assist greatly in future exploration of the Arctic Islands.

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