Question: I’m teaching A-level Glaciation, and we have to talk about Ice Sheets and the landforms that they create and the one that is talked about often is an Ellipsoidal Basins especially related to the Laurentide Ice Sheet and Minnesota . I was wondering if you have any diagrams or simple explanation to explain the formation of this landform .
– David
Hi David, Thanks for your question. Ellipsoidal basins are not often spoken about so finding appropriate resources are quite hard. Essentially an ellipsoidal basin is a former river valley which has been both widened and deepened from subglacial activity beneath an ice sheet. A more common geographical term used to describe these processes, and the basins they form is glacial overdeepening.
The Laurentide Ice Sheet is used as a classic example as its successive advances during the Quaternary Period led to the formation of the Great Lakes and the Finger Lakes in North America. You can read more in detail about ellipsoidal basins here. Hope this helps.