On Saturday November 8th 2008 we went to explore local and Western Maryland Geology. Our first sight was right off campus. We stopped at the Paint Branch Stream. Here we analyzed the affects of the river on the surrounding environment. Taking into account the movement of the stream we were able to deduce the movement away from the point-bar towards the cutbank. On the cutbank we were able to see different layers. From observations of these layers, such as their composition, the energy of the stream over time was evident. Clay deposits show that when they were formed the stream was sedentary with out energy. The lack of energy in the water allowed the small particles to settle to the bottom and form a layer of clay. The rocks on the point bar and those visible in a rocky layer of the cutbank showed evidence of the now energetic stream. The rocks had been tumbled into round and corner-less shapes. Had the stream been energy-less it would have been unable to move the rocks down stream from their bedrock and they would still be jagged. The harder quartz appears to be more abundant because of its strength, taking longer to be worn down than other weaker rocks. From the point-bar you can also tell that the stream has not always been the same level. The buildup of leaves on large rocks and trees all point in a uniform direction, downstream. The only plausible way for these leaves to be uniform in such a way would be for the water level in the stream to periodically rise so that leaves floating in the water could become caught on the obstructions. The streams movement also has an affect on the cutbank, it wears away at the soil there ultimately moving the stream towards it and away from the point-bar. The movement of the river causes the vegetation on the point-bar side to be far younger than that on the cutbank.
Our second stop was a railroad cut in Western Maryland, Fredrick County. This site is part of the Newark Supergroup. Here we were able to see sedimentary rocks that formed in the Late Triassic and Early Jurassic. The rocks here were fine, smaller than beach sand but big enough that you could still see the individual grains. These rocks would have probably formed in a lake that was void of energy to allow the sediment to easily fall to the bottom. The sediment in these rocks appears to be only one type of rock, although it does contain some mica. The strata at this location was not horizontal, it had a Dip of 28 and Strike of 32 East.
Our third stop was also part of the Newark Supergroup. The rocks at this site were made of beach sand-like grains. This tells us that the sandstone was formed in a faster moving environment than stop two. This faster moving environment was probably a river. Also the beds at stop three were cross beds, where those at stop two were single layers.
Our final stop was an out crop of a diabase of igneous rock. This igneous rock did not show any internal structures like those at the previous two spots. The orientation of the diabase relative to the sedimentary strata is that it is at an angle through the perpendicular sedentary strata. From this orientation you can tell that the sedimentary rocks came first. The diabase forms in the sedimentary strata after the cotenants are pulled apart. This field trip was educational in showing us the effects of hydraulic power on the Earth. We were able to see its effects both right off campus and in Western Maryland.