Ground Penetrating Radar Provides Evidence for the Previously Unrecognized Danaher Channel near Seney, MI

Abstract

It is common belief that glacial meltwater from Lake Superior flowed to the Atlantic Ocean through a northeasterly channel before the Sault Ste. Marie channel existed. However, recent geomorphological evaluations of Upper Michigan suggest that a Holocene-era channel (Danaher Channel) cut through Upper Michigan, which provided a path for the meltwater from present day Lake Superior to Lake Michigan. Ground penetrating radar (GPR) data (800 meters in length) were collected roughly 11 kilometers southeast of Seney, MI, to provide subsurface evidence for this theory. GPR is a survey method that utilizes antennae that transmit electromagnetic (EM) energy into the ground, which reflect off materials of different dielectric properties. The reflected EM waves return to the antennae and create an image of the subsurface. A Sensors and Software pulseEkko100 GPR system was used to collect two transects with step sizes of 0.5 meters and an antennae frequency of 100MHz. Using the EKKOproject software program, line views of the transects were processed by adding wiggle traces and using Dewow+AGC gain to precisely image the stratigraphic properties of the facies. Semi-continuous layers truncated by sub-horizontal layers provide evidence for the Danaher Channel. Further GPR lines are proposed to more accurately determine the path of this channel.