26 May 2016
This is fun! Check out this photo of a trench wall during a sewer line installation through the Waubonsee Community College campus, southeast of Chicago, Illinois, in 2006:
The photo is from my colleague Dave Voorhees, a professor at Waubonsee Community College. Dave says:
The handle of a trowel stuck into the trench wall is visible in the middle left side of the image. The top third of the image shows evidence of cryoturbation seen in many gelisols, that is here formed in an organic-rich (O horizon) silt over diamicton (till) of the Batestown Member of the Lemont Formation formed during the Quaternary invasion of northeast Illinois by the Lake Michigan Lobe of the Laurentide Ice Sheet. The lower 2/3 of the image are diamictons, sands, silts and clays that have been deformed by an over-riding glacier during the Putnam Phase of the Michigan Subepisode (~18,0000 to 17,500 yr B.P.). Of note is the glaciotectonic thrust fault from bottom left to top right.