Paleowind (11,000 BP) Directions Derived from

Lake Spits in Northern Michigan

Frank Krist Jr. and Randall J. Schaetzl

We report on the characteristics of several, previously unstudied, late Pleistocene spits in northern lower Michigan. Each spit developed as strong waves eroded a headland or island within the Main and/or later stages of glacial Lake Algonquin. Most have ESE to WNW orientations with prominent recurved hooks at their ends. Some are as long as 20 km. Sedimentologically, the spits contain thick (several meters or more) sequences of sand and well-rounded gravel. We suggest that summertime winds during the spits formation (11,800 to 10,500 BP) were both very strong and dominantly from the E and SE, based on the following data: (1) their ESE (source, or head, of the spit) to WNW orientation, (2) the presence of steep, wave-cut bluffs on the east sides of the islands and headlands, sand (3) spit locations (on the northeastern shore of Michigans lower peninsula, coupled with their absence on the northwestern shore, just 100 km away). Wind direction data provided by these spits agree with paleoclimatic models that suggest that the Laurentide Ice Sheet had developed a strong anticyclonic circulation. The near lack of archeological sites from this time period in the northern lower peninsula, which was surrounded by Lake Algonquin at the time, supports the notion that the climate of northern lower Michigan was inhospitably cold and very windy in the late Pleistocene. 2001 Elsevier Science B.V. All rights reserved.