Archive for February 20th, 2018

A warm February afternoon in Spangler Park

February 20th, 2018

Wooster, Ohio — The weather today was extraordinary. It reached at least 70°F in our little Ohio town, which must be near a record. Greg Wiles, Nick Wiesenberg and I took advantage of the warmth and sunlight to hike through Spangler Park. I think the day should be memorialized with a brief blog post. Greg and I are on research leaves this semester, so it is easy for us to break away from our computers to take jaunts like this. (Sorry, Meagen, Shelley, Alex and Karen!)

Above is a familiar exposure to most Wooster Geologists. It is an exposure of glacial sediments visited by dozens of department field trips. Recently a slump block descended across the face of it, exposing new material. Nick is standing on the block, and Greg’s dog Arrow is watching at a prudent distance.

Chloe Wallace (’17) posted this nice description of this outcrop two years ago:

This photo is taken from across Rathburn Run, from the point bar. This outcrop is much younger in age, from the last time Ohio was affected by glaciation. During the Last Glacial Maximum, specifically the Pleistocene, glacial debris flows deposited the bottom section of the outcrop. The sediment is characterized by a fining upwards sequence and has two scales of support. Some areas of the deposit are composed of large grains within a matrix-support due to debris flow. Other areas of the deposit are composed of sandy conglomerate rock that is grain supported. Overall the sediment is poorly sorted and contains glacial erratics within the sediment, including boulders made of gneiss, granite, and some sedimentary rocks.

A channel cut through the original glacial debris flow deposit and was eventually filled in by wind-blown silt, also known as loess. Loess is characteristically different from the glacial deposit at the bottom of the outcrop. Loess breaks in sheets, which causes it to have steep angles. Overall, the history of this outcrop is that approximately 15,000 years ago debris flow events deposited the glacial sediment at the bottom of the outcrop, then a channel cut into the deposit and that channel eventually filled with eolian (wind-blown) silt.

Classic geology on a beautiful day.