Joint 52nd Northeastern Annual Section / 51st North-Central Annual Section Meeting - 2017

Paper No. 66-2
Presentation Time: 1:55 PM


WELLS, Neil A. and POSEDLY, Peter M., Department of Geology, Kent State University, 221 McGilvrey Hall, Kent, OH 44242,

During times of Whittlesey lake levels (ideally 223 and 226 m but here, broadly, beach ridge crests at 219-229 m), the Defiance Moraine formed a variably submerged to emergent barrier across the western Erie basin, with shorelines on both sides. Frequency plots of probable beach base and crest elevations may permit splitting out up to 10 possible minor shorelines (counting and correlation degrade into subjectivity) in addition to the standard two, with individual profiles showing up to six. , Correlations to the main two beaches farther west along the edges of the Erie trough indicate that the “226" beach shows about 1.75 m statistically significant uplift in the center of the basin relative to basin margins, while the “223" beach shows none. This can be explained by draining c.6 m of water, less than from 226 m to the mid-basin lake-floor plain at 210-220 m. 

 Shorelines above 225 m are crossed by broadly developed parabolic dunes, which are in turn cut by lower shorelines ≤c.224 m that do not show uplift. One dune’s crest is bevelled nearly flat below 223.5 m, but remains pristine above. Dune development probably required a regression to below 219 m or so to expose the local lake floor (and probably below 207 m), and then a transgression to c.223.5. This implies a significant lowstand (the Arkona-Ypsilanti stage?) between higher and lower Whittlesey levels, rather than before or after. 

 Erie trough dune fields evince winds blowing uniformly due east during multiple regressions, but Whittlesey beaches are larger on the east side of the Defiance moraine than on the west, having statistically significant greater heights (2.08 vs 1.38 m), higher tops (223.99 vs 223.81 m) , and lower bases (221.91 vs 222.46 m). 1.5 times higher waves on the east side could be explained by strong katabatic winds draining westward down the Erie trough ice tongue or by having a long fetch in the east. Modern-strength winds from the west (mean = 5.74 m/s) would produce a significant wave height of 0.67 m over the 63 km fetch from Fort Wayne. Forming waves 1.5 times higher would require a 305 km fetch to the east, assuming modern-strength winds from the east (3.95 m/s), or only 3.4 to 3.6 m/s over the 370-470 km fetch suggested by earlier authors.

  • WellsGSA.pptx (48.7 MB)