Baraboo Rhyolite Research Paper

INTRODUCTION Baraboo, Wisconsin is one of the most geologically interesting locations in the world. With the mere act of hiking to different locations, one is able to see structures spanning from around 1.6 billion years ago to the end of the Ice Age all in the modern day. Over massive scales and over long time periods, Baraboo exhibits a variety of features, from a double plunging syncline to a rock made of two different types of metamorphic rocks. The location has once had volcanoes, mountains, and the entire ocean covering all but a few sea stacks. The great changes that have occurred here is not unique to Baraboo, but it is the ability to deduce such a complex history from observing the different landmarks that makes it such an interesting place to discover.

OBSERVATIONS
1. Igneous Rocks
The only igneous rock we observed during the Baraboo trip was the Baraboo Rhyolite. Located by the highway, we took note the rock’s red color and lack of cleavage (see Appendix 1.1), signifying that it was made of potassium feldspar and quartz. It had no obvious bedding, and we quickly concluded it was the Baraboo Rhyolite due to its color and lack of prominent features (e.g. fossils). However, we did notice that the rock had the faintest

Since we had already identified quartzite, we had to determine what the other rock was. Since quartzite is metamorphic, we deduced that it was also metamorphic. At the Van Hise rock, we saw that the rock was a black color. Both it and the quartzite were vertically dipping, but the phyllite was prominently foliated. It had fine grains, so we knew it to be phyllite. At this location, the cleavage folds differed from each other (see Appendix 1.7). In particular, those of the phyllite seemed more flexible, so the rock was softer. The phyllite was wedged between two quartzite structures. One of them had tension gashes on it (see Appendix