Ribbed moraines in northern Manitoba, Canada: characteristics and preservation as part of a subglacial bed mosaic near the core regions of ice sheets

The demonstrated fragmentary nature of ribbed moraine fields, the inherited signature of the till within these fields, the secondary patchy drumlinization of the ridges, and the more abundant granitoid outcrops in areas of intense modification all suggest that subglacial ribbed moraine formed from pre-existing sediments and were later preserved and/or partially reworked through a regional mosaic of shifting subglacial bed conditions. We therefore make the case that pristine (unmodified) moraines were preserved beneath stable sticky spots. We support a link between ribbed moraine and widespread cold-based and/or dewatered subglacial conditions in inner-core regions of ice sheets, but for reasons of preservation, and not necessarily formation.