When I initially was told we would be taking a geological tour around campus, I was wondering what exactly we'd be looking at. I didn't think of a water-site as immeditely factoring into a geological tour, but the ESEM students took us to the section of Mill Creek behind Batten House and talked about it's relation to geology. One of the students mentioned how rivers and water beds form by running through softer rock. If at first softer rock is blocking a water sources progress, eventually the water will wear down this rock and create an elongated pathway. As we walked through campus, the ESEM students shared how the time frame in which Bryn Mawr College's various buildings were built was also reflected by the rock used to make it. Pembroke and Radnor are made of wichenschist, Taylor and Merion of Baltimore gnisse. Many of the dorms also have bits of mica within the building rock "brick", a rock that literally sparkles in the sunshine and adds a shine to the outer building. I also found out that limestone is absorbant of water, and the rocks outside the gym doors that I thought were purely there for decoration suddenly gained an actual purpose. These rocks were placed immediately under a pipe on the roof of the gym that dripped excess rain water; the limestone caught the water and prevented it from spreading too much. Upon examination, it was easy to see where the limestone had been affected; it had turned from a starker white to a significantly green color in some spots.
