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Welcome to Picnic Point Penninsula of the Lakeshore Nature Preserve!
Earthcaches have no physical container or log to sign. Instead, email or message me the correct answers for these questions and claim your earthcache smiley.
1. What do geologists call the three layers of the earth?
2. Is there a tectonic plate somewhere beneath your feet?
3. Which lobe of the Glacial ice sheet moved through this area?
4. What was deposited to create Picnic Point Peninsula?
5. Examine the shoreline at GZ. Then move to the waypoint near the shoreline to the Northwest of GZ. Briefly describe what you see at each of the peninsula's shorelines and point out differences between them.
The information found below and your observations at GZ will help you discover the correct answers.
Please observe the following as you visit the Lakeshore Nature Preserve: https://lakeshorepreserve.wisc.edu/visitor-etiquette/
https://lakeshorepreserve.wisc.edu/visit/plan-a-visit/
How did this Penninsula get here?
Geologists surmise the earth formed in space 4.6 Billion years ago when swirling gasses and dust particles began smashing into each other over and over and over again. Gravity and heat were exerted on these materials, and over time, the heat melted some of the materials. Lighter materials separated from heavier materials, and the lighter, molten liquids rose to the surface of the earth. Once on the surface, cooling began and formed a crust on top of the liquid, molten layer, while heavier material was pulled downward. Over a long period of time, the earth developed three layers: the core (heaviest materials), the mantle (molten materials), and the crust.
The earth’s crust is broken into pieces called tectonic plates, which float on the molten layer of the earth. Tectonic plates are always shifting and drifting as they bob about on the earth’s mantle of molten liquid. As Tectonic plates move around on the mantle, they may also collide with each other. In the collision, the heavier plate can slip its edge under the edge of the lighter plate. When the rock crust dips under and is pushed further into the earth’s molten layer it may melt again, become lighter, and be pushed back out to the surface as lava. Earth’s first landmasses were created in this manner as little islands built up of cooled lava on the crust. Over time these landmasses were pushed together by bumping and shifting of tectonic plates to form a bigger and bigger landmass. This process of landmass creation began approximately 4 billion years ago, which was RELATIVELY shortly after earth’s creation.
Eventually (~250 million years ago) the earth’s landmass was bumped and pushed together into a single supercontinent, known as Pangaea. This ancient, large continent was located near the earth’s equator before it was ripped apart (~180 million years ago) into smaller continents, and finally into the continental shapes that we know today. After being broken up, the continents continued to migrate with tectonic plate shift until reaching the various latitudes where we associate them today. Tectonic plate shift is an ongoing process that continues to bring changes to our world, typically at such a slow rate that it is not recognized by ordinary humans whose feet are planted on various tectonic plates around the world, however, scientists are able to recognize it. Plate collision can also be responsible for what we could consider catastrophes such as earthquakes and volcanoes.
At the site of this earthcache, another force went to work on land formations. Great glacial sheets of ice, hundreds of feet deep developed and moved through, scouring the land of its hills, valleys, rocks, mud, silt, sand, and anything else that was in its path. The ice picked up all this debris and moved it along within the ice flow. The glacial ice sheet crept forward from north to the south in several different lobes. The lobe that last crossed this area, known as the Green Bay Lobe, had the least obstacles to impede it and reached as far south as Rock County in Wisconsin before the glacial era began to recede. Most of Wisconsin found itself under ice beginning about 25,000 years ago, and ending about 10,000 years ago.
Glaciers melted when the ice age ended. The debris that was picked up by the ice during its journey (rocks, mud, sand, silt, dirt, pebbles, boulders) was deposited back onto the land. Some of it was left in piles. Some of it was carried off with meltwater causing ridges and squiggles of new landforms. New lakes were formed in low areas, and new riverbeds were created by water run-off.
Picnic Point Penninsula is made up of piles of glacial debris. A peninsula is a geological landform that juts out into the water, surrounded almost entirely by water, but attached to the mainland at some point. Peninsulas may be very large such as the Iberian Peninsula in Europe which contains the countries of Portugal and Spain, or very small, perhaps with room to fit only a lighthouse on it. Picnic Point is nearly a mile long, and has long been a favorite location for University students and locals for over 100 years. Today Picnic Point peninsula is part of the Lakeshore Nature Preserve, with hiking/running/dog walking trails, and reservable fire circles.
Permission to place this cache was given by Laura Wyatt, Program Manager and Gary Brown, Preserve Director The Lakeshore Nature Preserve through the permitting process described in the following links. Geocachers are responsible for following all established rules, including any established for Covid virus. Links: 1) Policy for geocache placement on land managed by University of Wisconsin Lakeshore Nature Preserve, 2) Geocache Placement Permit Application
Resources:
Geology of the Lakeshore Nature Preserve. https://lakeshorepreserve.wisc.edu/geology-of-the-lakeshore-nature-preserve/
Lakeshore Nature Reserve Picnic Point. https://lakeshorepreserve.wisc.edu/visit/places/picnic-point/
Lakeshore Nature Reserve Parking: https://lakeshorepreserve.wisc.edu/visit/places/parking/
National Geographic Society. Continent. https://www.nationalgeographic.org/encyclopedia/Continent/12th-grade/
National Ocean Service. What is Tectonic Shift? https://oceanservice.noaa.gov/facts/tectonics.html
National Park Service. Ice Age: Geology of Ice Age National Scientific Reserve of Wisconsin. NPS Scientific Monograph No. 2. https://www.nps.gov/parkhistory/online_books/science/2/chap1.htm
Wisconsin Glacier Springs. Wisconsin’s Glacial Legacy. https://wisconsinglacier.com/wisconsins-glacial-legacy/
Wisconsin Geological and Natural History Survey. Ice Age Geology. https://wgnhs.wisc.edu/wisconsin-geology/ice-age/