Drilling logs, cuttings samples, and a limited amount of split-tube
samples--acquired as a by-product of a crystalline basement drilling project--
provide evidence for informally naming nine new till units in central
Minnesota. The Elmdale till may represent the first Pleistocene ice advance
into central Minnesota. Other tills of northwestern provenance are the
Eagle Bend, Meyer Lake, Green, and Browerville. Although shale is generally
rare, these tills typically contain appreciable amounts of Cretaceous rock
fragments, chiefly from the Greenhorn Limestone. The Second Red, First Red,
Sandy, and Red Sandy are pre-Wisconsinan tills of northeastern provenance.
They compose only a minor portion of the Pleistocene deposits in the Todd
County area, but indicate alternate northeastern and northwestern ice
The surf icial Wadena till had a northeastern source, as indicated by
lithology, texture, and drumlin orientation. Its relatively high carbonate
content, which led earlier workers to ascribe a northwestern provenance, was
deri ved through incorporation of older drif t.
The Elmdale, Second Red, and Eagle Bend tills are thought to be pre-Illinoian;
the First Red, Meyer Lake, and Green tills, pre-Illinoian or Illinoian;
the Sandy and Browerville, Illinoian; and the Red Sandy, Illinoian or
early Wisconsinan in age. A new radiocarbon date of 36,970 B.P. from a wood
sample above the Wadena till supports an early Wisconsinan age designation
for the surficial till over much of Todd County.
Meyer, Gary N..
RI-34 Subsurface Till Stratigraphy of the Todd County Area, Central Minnesota.
Minnesota Geological Survey.
Retrieved from the University of Minnesota Digital Conservancy,