Glacial and Sea-Level History of Southwestern Cumberland Peninsula, Baffin Island, N. W. T., Canada

Southwestern Cumberland Peninsula has been glacierized at various times by eastward flowing Laurentide ice, by an expanded Penny Ice Cap, and by fiord and valley glaciers fed from cirques. Two major weathering zones (A and B) and a fivefold subdivision of the younger zone (A) are recognized. The zone boundaries are marked by end and lateral moraines, some of which are related to raised marine deltas. Radiocarbon dates and amino acid age estimates on fossils from these deltas and correlations with the stratigraphic record of northern Cumberland Peninsula allow establishment of a tentative “absolute” chronology.The oldest terrain is that glaciated before the last interglaciation. The last glaciation is subdivided locally into the Duval, Outer Usualuk and Ranger stades, named for the end and lateral moraines which mark their maximum extents. During the Duval Stade (ca. 100,000 to 60,000 yr BP), Laurentide ice filled the inner one-third of Cumberland Sound and ice from local sources filled Pangnirtung and Kingnait fiords. Relative sea level was 100 m above present at the ice margin (Duval marine limit). Retreat from the Duval stadial maximum was followed by a re-advance of Laurentide ice and by coastal emergence. Much of the area was glacierized during the Outer Usualuk Stade (ca. 40,000 yr BP?) when relative sea level was 108 to 120 m above present at the ice margin (Shark marine limit). Retreat was followed by coastal emergence. During the Ranger Stade, Laurentide ice reached the head of Cumberland Sound and coalesced with the western lobe of the Penny Ice Cap, and outlet glaciers from the southern part of the ice cap reached 20 km beyond their present positions. General deglaciation from the Ranger stadial maximum and coastal emergence from the Holocene marine limit began about 8700 yr BP. Relative sea level at the Laurentide margin at that time was 88 m above present. During an early Holocene warm interval, Penny outlet glaciers receded rapidly and were at or behind their present margins by 7000 yr BP. The Laurentide ice retreated much more slowly, forming eleven recessional moraines before it uncovered the head of Clearwater Fiord at 5700 yr BP. The lowland between the head of Cumberland Sound and Foxe Basin was deglaciated between 7000 and 5700 yr BP by an eastward calving bay. After separation from Laurentide ice, the western lobe of the Penny Ice Cap readvanced about 4500 yr BP to form the Outer Penny Moraine. This was followed by recession during a warm interval which was followed in turn by several smaller advances.The Holocene marine limit forms a synchronous strandline declining beyond the Ranger Moraine and intersects present sea level about 100 km beyond the Laurentide margin. Behind the Ranger Moraine it is a metachronous feature which dips in the opposite direction. All dates can be fitted to a series of relative sea level curves, that show glacioisostatic emergence at the head of Cumberland Sound grading to submergence at the mouth of the Sound. The zero isobase on emergence has migrated about 100 km westward since 8700 yr BP.