Nathan Birecki
GLG103 Peters
April 19. 2015
Hometown Geology: Geologic History Papago Park Papago Park Pediment if an interesting part of Arizona from a geologic standpoint. Metarhyolite is the oldest rock that is exposed on the surface at Papago Park and it is from the Precambrian era. The Metarhyolite was produced from a low-grade metamorphism implying that Papago Park once had some volcanic activity. The Metarhyolite is composed of Rhyolite, Pumice, and Greenstone. Two different forms of granite intrude upon the Metarhyolite they are Tovrea and Camelback Granite. Basalt and Aplite dikes intrude upon both the granite units and the Metarhyolite. There is also an unconformity that exists between the Precambrian and Tertiary rock units however there are no rocks from either the Paleozoic or Mesozoic era. Uplifting of the Precambrian era rock units occurred during the Tertiary era resulting in the deposition of rock beds that contain both sand and siltstones. Some volcanic activity produced ash that has been transported via weathering to various locations throughout Papago Park. The deposition of Alluvium from the Quaternary era indicates there was once a flowing river that is currently a dry riverbed. Landslides deposited the Stadium and Zoo Breccia members as the formation known as the Camel Head. There are both normal and reverse throughout Papago Park but there are no strike-slip faults. The majority of the faults are moderately dipping around 45 degrees that explains the repeat of rock unit structures. Papago Park is beautiful area that is a popular destination for many people as it is a great place for hiking, sight seeing, and enjoying the Arizona heat.