Participants will explore landscape
By Holly Neumann
Terry Gerlach, a retired geologist and geochemist, will discuss glacier geology from 10 a.m. to noon Saturday, May 11, at Jorgens Park Preserve.
The program will begin at ScandiHus, 280 N. Main St., Scandinavia.
“I will begin by saying a few words about myself and my experience as a geologist,” said Gerlach. “Then I will give a talk providing background information on the history of the last glaciation event, emphasizing in particular its impact on this area of central Wisconsin and pointing out processes that affected landforms and deposits that they will be seeing during the park walk.”
Following a period for questions and comments, the group will drive to Jorgens Park, where Gerlach will point out geological features.
“Then we will do the walk exploring, examining and discussing each of these features, perhaps taking some samples,” he said.
The trip will focus on three main features of the park’s glacial geology:
• A drumlin landform on the northeast end of the park shaped as the glacier advanced across the area and comprised of sandy till with large boulders of Wolf River Granite containing large feldspar crystals.
• The ubiquitous glacial outwash deposits of sand, silt and gravel that made groundwater aquifers, pastureland, cornfields and irrigation agriculture possible.
• As glacial melt water surged back to the east during glacial retreat, it often buried stranded ice under outwash deposits, which led to a landscape of ups and downs after the buried ice melted and the overlying sediment collapsed and sunk inward to fill the void. This is the origin of Wisconsin’s most common lakes – the kettle lakes like Silver Lake.
“From the beginning of the Jorgens Park Preserve idea, educating and enriching the public’s awareness about our area’s natural heritage has always been a principal motivation and justification for its existence,” said Gerlach. “This event will showcase the glacial geology of the park as the product of The Wisconsin Glaciation — the last great continental ice sheet of the Ice Age and mainly responsible for the park’s landscape. The glacial geology is fundamental and will play an important role in how the land will respond environmentally, ecologically and economically to future weather, climate and human forces.”
The event is free and intended for high school students and older.
All money spent at ScandiHus during the group’s meeting time will be matched with a donation to the Friends of Jorgens Park Preserve.