SUBGLACIAL MELTWATER ORIGIN AND SUBAERIAL MELTWATER MODIFICATIONS OF DRUMLINS NEAR MORLEY, ALBERTA, CANADA

Drumlins in the Bow valley west of Calgary, Alberta, are interpreted a s the product of subglacial and subaerial meltwater erosion. On the si des of the Bow valley highly elongated, streamlined, first-generation drumlins are aligned in an en-echelon fashion and are not significantl y modified by post-glacial processes. In the valley bottom, scalloped, stubby, irregularly spaced second-generation drumlins are found in cl ose association with valley fill. The drumlins are composed of bedrock and diamicton, and some are overlain by a thin gravel veneer. Stratif ied gravel is found on the leeward flanks of some second-generation dr umlins. Meltwater erosional forms (s-forms) found on the limestone bed rock up-flow of the drumlins, and crescentic furrows around their prox imal ends, indicate that subglacial meltwater beneath the Bow valley i ce was probably the main erosive agent responsible for the shaping of the drumlins. The second-generation drumlins arc believed to be the re mnants of the first-generation drumlins that were dissected and rework ed by postglacial, subaerial meltwater flow(s). Meltwater drainage fro m ice-dammed glacial Lake Kananaskis and possibly other glacially damm ed tributary valley lakes, resulted in the deposition of megaripples ( 3.5 m high, 40 m wavelength) 8 km down-flow from the drumlins and reve rse eddy deposits on the flanks of the drumlins. Post-glacial Bow Rive r incision and terrace development has continued to further sculpt the se forms.