The glacial border of the Laurentide ice sheet in the western Canadian Arctic is commonly recognized with Herschel Island in the Beaufort Sea expressing its subaerial northwestern limit. Ice-rich and diam- ictic deposits build up the island and they are inter- preted to result from a push moraine that dumped material in the area. The deposits were likely exca- vated from the nearby Herschel Basin, a prominent bathymetric depression on the sea floor found in the SE of the island. We test this glacial interpretation by comparing the clay mineral distribution in the area. Surface samples have been collected on- and offshore, from Herschel Island and the Yukon Coastal lowland, and from the Beaufort Sea shoals with sampling sites placed in- and outside of the supposed ice sheet extension.