Development of End Moraines in East-Central Baffin Island

Five steps in the accumulation and deposition of end moraines are postulated from observations of profiles and ablation features around the south end of Barnes Ice Cap. This end of the icecap is generally more expanded than it was throughout the past century, but a retreat, producing end moraines, has begun on the southern and southwestern sides. Dirt is raised to the surface on shear planes along a narrow fringe of black ice around the edge of the icecap. This is till, exposed in small amounts by 5-7 feet of ablation each summer. This film of debris slips and slides down the 10°-30° marginal slope and gathers over the lower ice slope. Where the ice becomes blanketed by 3 feet of ablation moraine and dirt-filmed ice above melts back rapidly, a trough develops parallel to the margin, isolating a steep-sided moraine on an ice core. After many years this material is let down irregularly to solid ground by flow of the till cover, cuts by transecting streams, and lateral undermining of the exposed core ice.