We learned about how topography can affect water flow and how water flow can influence topography. Many people donned 3-D glasses to examine a shaded topographic map that showed the mountains, river valleys, and undersea landforms of the whole globe. We saw undersea trenches, tall mountains, and the Mississippi River Valley. Then we used the U of St. Thomas’s stream simulator that allowed us to interact with water flow on a landscape and examine the processes that shaped those landscapes. We made eddies, formed potholes, and tried out sediment levies.
We tried our hand at paleolimnology, or the study of the history of lakes. We learned that soil cores from lake bottoms, or beds, can reveal the environmental history of the area. Sediment appearance changes with the seasons and can be examined to show the historical climate of the area using chemical analyses, pollen counts, and many other techniques. Some of the scientists were using the chemistry of shells in different lake sediments to reconstruct temperatures! We also looked at diatoms that are commonly found in lakes and sediments in Minnesota. Diatoms are algae with silicate (glass!) shells and their shells remain in soil and lake sediment after they die.
We also looked at different types of rocks to learn about the geology of Minnesota. We examined the difference between sedimentary and igneous (volcanic origin) rocks with hand lenses and microscopes. We tried to determine whether the rock was quickly cooled or slowly cooled based on the size of crystals (bigger crystals result when rocks are slowly cooled). We examined how metamorphic rocks are different from their composite parts (both igneous and sedimentary).
Finally, we took all of our new-found geologic knowledge and mixed it with googly eyes to make fine art! Thanks again to Dr. Kevin Thiessen and the scientists from University of St. Thomas. We had a total of 188 visitors this week (76 kids, 112 adults, and 118 people stayed long enough to alter hydrology and examine rocks or make their own pet).