PRELIMINARY MAP OF THE SURFICIAL GEOLOGY OF THE BURNSIDE 7.5 MINUTE QUADRANGLE, LAPEER COUNTY, MICHIGAN

The Burnside 7.5 Minute Quadrangle is located on the thumb of Michigan in northeastern Lapeer County. The preliminary surficial geology of the study area was constructed using information from the United States Department of Agriculture’s soil survey. The surficial geology within the Burnside Quadrangle has been studied sporadically for over 100 years, but has never been mapped at a 1:24,000 scale. The surficial geology is complex due to the fact that it lies within the interlobate area that formed between the Saginaw and Huron lobes of the Laurentide Ice Sheet following the last glacial maximum. Surficial deposits include loamy till (55% of the study area), clayey till (11.5%), glaciofluvial outwash (9.5%), organic deposits (7.5%), and glaciolacustrine deposits (1%). Collectively, about 1% of the surficial deposits in the study area are surface water, gravel pits, wave-worked till, and alluvium. A LiDAR-based digital elevation model (DEM) of Lapeer County has improved the quality of topographic data for the area. As a result, several features have been identified in the area that were either previously unidentified or unresolvable using 1/3 arcsecond DEMs, including infilled kettle lakes in outwash fans, scour lakes, morainal ridges, and strand lines located just outside of the quadrangle.

In addition to glacial, glaciofluvial, and ice-marginal deposits, the study area also contains about 8.7 km of the Imlay channel, including the proposed sill of the channel. The Imlay channel has been described as an outlet that drained one, none, or several stages of glacial Lake Maumee, which formed in the Ancestral Lake Erie (ALE) basin. Water in the channel was transported east to west from the ALE into the Lake Michigan basin. However, the LiDAR-derived DEM, as well as a series of geotechnical bore logs near the channel’s sill, suggest that the area may have been infilled with alluvium from a kame deposit that runs along the NW-trending eastern flank of the channel and that Clear Lake, one of the few natural lakes within the study area, may be the remnant of a backwater to the channel when it was active.