Drumlins Are One of the Keys to Decoding What the Ice Age Floods Actually Did

Drumlins are among the most diagnostic landforms left by the Ice Age, and Randall Carlson argues they are also among the most misunderstood. The conventional explanation treats them as passive accumulations of glacial till shaped by the movement of ice overhead. Randall's reading goes deeper - literally.

The process he describes begins with water under pressure moving through the chaotic substrate beneath a glacier. That pressurised water erodes upward into the base of the ice, creating a distinctive cup-like cavity - almost the inverse form of the drumlin that will eventually result. As the fluvial processes take hold, they begin to organise the disordered glacial material. The physics is consistent and directional - the blunt end of the resulting landform faces into the current, and a long tapered tail extends downstream. The shape of every drumlin is therefore a frozen record of the direction and nature of the subglacial water flow that produced it, making drumlin fields one of the most reliable tools available for reconstructing the hydrology of the Ice Age landscape.

Join Randall in the field in New York State for his Finger Lakes Tour, Aug 30 Sep 5, 2026