No. 66: Nov-Dec 1989
Cross section of a typical drumlin, as figured in CAROLINA BAYS, etc.
Canadian geologist J. Shaw is now trying to break out of this philosophical prison.
"According to Shaw, heat from the Earth formed huge lakes of meltwater that remained trapped beneath the North American ice sheet. As the sheet began to retreat near the end of the glacial age, the water broke through and flowed in torrents down to the Gulf of Mexico and Atlantic Ocean. While flowing under the ice cap, water would have surged in vast, turbulent sheets that sculpted and scoured drumlins. Each flood lasted until the weight of the ice cap once again shut off the outlet of the covered lake, Shaw says."
Shaw goes on to estimate that one large drumlin field in Saskatchewan was created when 84,000 cubic kilometers of water was discharged. Just this single episode would have raised global sealevels by about 10 inches in a few days or weeks. Imagine what happened as this water flowed across North America.
Many geologists look askance at Shaw's theory of drumlin formation.
(Monastersky, R.; "Hills Point to Catastrophic Ice Age Floods," Science News, 136:213, 1989.)
Comment. The famous Channelled Scablands in the Pacific Northwest are thought to have been scoured out when an ice dam broke unleashing the Spokane Flood near the end of the Ice Ages. These land forms are described in our catalog: Carolina Bays, Mima Mounds. For details on this volume visit: here.