Waldo’s Rock was picked up by a glacier in West Central Minnesota, and then came to rest near the town of Marion, Iowa. Geologists have classified Waldo's Rock as metamorphic granite. Metamorphic means that the rock had metamorphosized or changed. This change was due to extreme heating and cooling that occurred at the rock's origin. This process created the texture and mineral composition of Waldo's Rock. Generally, the minerals and their respective colors are as follows: Quartz- clear pink and white Feldspar- Pink and red Mica- Dark Brown Amphibole- Black
Prior to construction of Waldo's Park, only one third of the rock was exposed. So during the park construction, dirt was removed to reveal three fourths of Waldo’s Rock which can now be seen as a magnificent piece of towering stone! During the excavation process, the rock formed a crack and began to separate, but it was shored up, so that no more movement would occur to cause a bigger crack. The crack that remained however, has provided a wonderful glimpse of the mineral composition inside this huge piece of metamorphic granite! And by the way, according to an official from the Iowa Geological Survey, Waldo's Rock is the oldest and largest known glacial erratic in Iowa!
To receive credit for this earth cache, email me the answers to the following questions:
- Describe the colors on the outside of the rock. What specifically causes these different colors?
- Look inside the large crack in the rock. Is the color and texture inside the rock the same as on the outside? Why do you think this is so?
- At its highest and widest points, estimate the height and width of Waldo’s Rock. Optional- post a photo of yourself by Waldo's Rock.