Definition of Illinoian in US English:



  • 1Relating to or denoting a Pleistocene glaciation in North America, preceding the Wisconsin and approximating to the Saale of northern Europe.

    • ‘These well-drained, sloping soils developed on Illinoian glacial till overlain with loess and have a compact fragipan that restricts root growth.’
    • ‘The Labradorean domain was more extensive in Minnesota and Illinois during the Illinoian glaciation than in the Wisconsinan glaciation.’
    • ‘This preserve is located on a käme (a hill or mound of stratified drift deposited by glacial meltwater) formed during the Illinoian glacial epoch.’
    • ‘During glacial retreat in the second of three advances, the flat Illinoian till plain was lain down in the lower third of the state north of Shawnee Hills.’
    • ‘The forest studied in Pike County, Illinois was on Illinoian glacial till in the Glaciated Section of the Mississippi River Border Division.’
    1. 1.1as noun the Illinoian The Illinoian glaciation or the system of deposits laid down during it.


Mid 19th century: from Illinois + -an.