A PRELIMINARY ACCOUNT OF LATE “WISCONSIN” GLACIATION IN MELVILLE PENINSULA, N.W.T.*

SUMMARY The glacial movements discussed here took place when deglaciation was well under way in northeastern North America. At that time, small, local centres of active ice dispersal developed. One of these lay in the area of eastern Foxe Basin. A smaller independent ice cap may also have existed on Southampton Island, or in northern Hudson Bay, at roughly the same time, as Bird suggests. Two major directions of ice movement across the peninsula are clearly indicated. North of Rae Isthmus (Figure 1 3. 1) movement appears to have been across the peninsula in a west‐northwest direction. A study of drumlinoids, roches moutonnkes, and crag‐and‐tail features suggests this conclusion. Swaths of limestone‐charged ground moraine tailing out towards the west from the eastern sedimentary lowland, and a decrease in the number of sedimentary erratics with increasing distance west across the upland, also support the theory of east‐to‐west glacial movement. An eastward projection of the line of general trend of these glacial indicators suggests that the source area for the ice lay in southeastern Foxe Basin. A second major direction of glacial advance is indicated on Rae Isthmus. Here drumlinoid topography with a pronounced southeast‐northwest alignment apparently resulted from movement to the northwest from a dispersal centre on Southampton Island or in northern Hudson Bay. Whether or not the ice moving westnorthwest from Foxe Basin and northwest from Southampton Island were contemporaneous in their passage across the peninsula is difficult to say. The apparentabsence of any interlobate material in the area north of Haviland Bay suggests that they were not precisely so; the more recent movement may have removed in its passage any débris left by the earlier one in the area over which it passed at this stage. Over most of the peninsula, then, the most recent ice movement appears to have been westward and northwestward as a broad lobe extending at its maximum from the latitude of Fury and Hecla Strait southward to at least the latitude of Repulse Bay. It may have been this ice which prevented south‐moving ice in northern Baffin Island 7 from crossing Fury and Hccla Strait or, if the north Baffin ice had previously crossed, which removed any evidence of southerly movement on Melville Peninsula. How far west the ice advanced is unknown. No glacial flow lines or movement indicators appear on Wales Island. The few which appear on Simpson Peninsula suggest an ice movement there from south to north. But it seems reasonable to assume that ice from a Foxe Basin‐Northern Hudson Bay source covered Committee Bay. portions of Simpson Peninsula. and the southern part of the Gulf of Boothia. To the north, the Melville Peninsula icc mass probably merged in the vicinity of Fury and Hecla Strait with west‐ and southwest‐flowing ice from northern Baffin Island. In the south it may have met ice moving north from northeastern Keewatin. Finally, it seems possible that an interlobate area existed in southern Gulf of Boothia between the Melville Peninsula‐Foxe Basin ice and ice moving in a northeasterly direction over Boothia Peninsula. When final ablation began in late “Wisconsin” time, the ice appears to have melted by downwasting. As the ice thinned, the high backbone of the peninsula was the first area to emerge. This event separated ice over Committee Bay from the larger mass over the peninsula and Foxe Basin. A kame moraine formed at the eastern margin of the remnant mass in Committee Bay (Figure 1 3. 2) With continued eastward retreat of the western margin of the peninsular ice, the west coast valleys were exposed and filled with outwash. Contemporaneously the west coast eskers were formed. These features were all built, however, in a comparatively short period of time. Ablation soon placed the western edge of the ice east of the stream divide, and subglacial and proglacia1 drainage to the west was impeded. As the Wisconsin glacial stage drew to a close, the melting of vast amounts of ice to the south raised the sea level, flooding low‐lying areas. Sea water probably lapped about the edges of ice in Foxe Basin, hastened its melting, and separated it from the residual ice over the peninsulaS (Figure 1 3. 3). The eskers and outwash material north of Repulse Bay and Haviland Bay, north of Barrow River, and on the eastern Palaeozoic lowland all formed in meltwater streams flowing radially to the ice margin Finally, the ice on the peninsula divided into two portions: a small remnant cap in the north, and a larger mass centred southwest of Parry Bay. The northern mass was the first to disappear. Ice remained longest in the area covered by ablation moraine and glacial drainage channels west of Parry Bay (Figure 1 3. 4). Here lay a heavily drift‐charged ice mass from which drained torrential, east‐flowing glacial streams capable of cutting the channels. By that time the ice over Foxe Basin itself had disappeared and the present Barnes Icecap on Baffin Island had shrunk almost to its present size. RÉSUMÉ Des traces de phénomènes glaciaires appartenant au Wisconsin inférieur ont été observers dans la Péninsule de Melville et résulteraient d'un faible avancement d'une masse de glace couvrant le Bassin de Foxe et la partie méridionale de I'lle de Baffin. Ce mouvement à travers la péninsule a probablement suivi deux directions. Au nord de l'Tsthme de Rae, l'orientation aurait été O.‐N.O. à partir d'une région‐source située dans la partie sudest du Bassin de Foxe. Sur l'Tsthme de Rae, l'avancement, à partir d'un point dans la zone septentrionale de la Baie d'Hudson, aurait eu une direction N.O. A son maximum, la glace aurait recouvert la Peninsule de Melville et la partie de la Baie Committee situee au sud de la latitude du Detroit de Fury et Hecla. La disparition de la glace resulta de la fonte sur place. Les hauts réliefs de la partie occidentale de la péninsule emergérent d'abord, divisant la masse de glace en deux lobes, dont l'un, le principal, occupait la peninsule et l'autre, plus petit, couvrait la partie méridionale de la Baie Committee. Une moraine fut construite le long de la bordure orientale de ce dernier. Suivant la disparition de la glace et l'émergence des vallées de la côte occidentale, des sables et des graviers de lavage furent déposés dans la Baie Committee dont les eaux se maintenaient pour un temps a un niveau élevé. L'ablation graduelle amena la bordure occidentale de la masse de glace peninsulaire à Test de la ligne de partage des eaux et l'ecoulement des eaux de fonte vers l'ouest fut ainsi interrompu. La montée du niveau de la Baie d'Hudson hâta la fonte de la glace dans le Bassin de Foxe et des îlots de cette glace furent séparés du lobe coiivrant la peninsule. Des lignes d'eskers radiaires furent constituées et la masse de glace résiduaire occupant la peninsule se divisa finalement en deux parties, au nord et au sud. la fonte du lobe septentrional fut rapide, tandis qu'au sud, la glace demeura assez longtemps sur une portion de territoire située à l'ouest de la Baie de Parry. Les lits de drainage que Ton peut observer aujourd'hui furent formés dans cette dernière région par des torrents et des cours d'eau coulant soit sous la glace, soit en bordure.