From NPS website:
STONES AND THEIR QUARRIES: As a National Park site, the National Mall preserves and protects these great stone symbols. Because of all the building stones, a visit to the National Mall is like a geology field trip across the globe, including rocks from all 50 states!
Where did all the rock on the National Mall come from? Locally quarried stone was used in the early part of Washington, DC’s history because transportation was too difficult to bring in stone from other parts of the country. As railroads expanded in the late 1800s, the choice of building material expanded as well. Suddenly, quarries from around the country were able to supply Washington, DC with rocks that showcased the unique geology of their region. Find out more about each type of rock used in the construction of the National Mall.
You will likely need a magnifying glass, in order to fully appreciate the true grandeur of these stones (especially if you are doing the whole DC M&M Trail). Are you ready?
ROCKS & MINERALS STUDIED HERE: Milford Pink Granite, Colorado Yule Marble, Pink Tennessee Marble, Alabama marble
LR#1 -- 38 53.354 W 077 02.958
Logging requirement #1-- How would you define the Milford Pink Granite's texture? specifically, would you consider the black biotite crystals to be minute, small, or large (list mm sizes)?
LR #2 -- N 38 53.354 W 77 02.991 (top of stairs/inside the monument – look down)
Logging Requirement #2 -- Did Contact Metamorphism leave any traces (non-calcium minerals, inclusions, etc.) in the marble at your feet?
COLORADO YULE MARBLE
The Colorado Yule Marble was formed by contact metamorphism. The parent rock of the marble is a Mississippian-age sedimentary rock called the Leadville Limestone. The limestone was heated and pressurized by the intrusion of magma that formed the granite of Treasure Mountain dome during the Tertiary period to create the Colorado Yule Marble.
LR #3, #4 -- N 38 53.357 W 077 02.994 (inside the monument, look up from near Lincoln)
Logging Requirement #3 -- Identify the COLOR of the Alabama marble as you look UP through the roof of the lincoln memorial. Evaluate whether this marble has its origin in pure calcium carbonite (thus pure white/translucent yellow) or if it has some dark mineral veins (styolites).
The ceiling of the Memorial, nearly 60 feet above you, contain panels of Alabama marble that has been saturated with to increase their translucency.
Logging Requirement #4 – Is the pedestal more than 50% Pure marble/limestone or more than 50% styolite?
PINK TENNESSE MARBLE (Lincoln’s Pedestal) The light grey to dark pink colored stone quarried near Knoxville, Tennessee is from the Ordovician aged Holston Formation. It is part of eastern Tennessee’s folded and faulted sedimentary layers associated with the formation of the Appalachian Mountains. Dark squiggly lines, called styolites, show where thin layers of mud and silt were squished between layers of limestone. There was enough pressure to partially recrystallize the limestone, though the result was not metamorphosed marble. In reality, the Pink Tennessee “Marble” is still a sedimentary rock--limestone. The quarry calls the limestone “marble” because it gets shiny when polished and is hard like marble.
METAMORPHIC -- Both of the marbles are formed when sedimentary stone (limestone, dolostone, sandstone) undergo heat and pressure. The more calcium carbonate (dead micro-organism skelatons) present in the sedimentary rock, the whiter the resultant marble. Minerals and inclusions add texture and color to the marble – adding pink, black, and more.
STYOLITES – layers of mud and silt that have been pressurized/squished between layers of limestone.
Please send your answers. Then post a found log. I will contact you if there are any problems or questions about your answers.
Congrads to captainmath & eightwednesday for dual FTF (First to Finish Logging Requirements) on this earthcache!
Wikipedia "Lincoln Memorial" http://en.wikipedia.org/wiki/Lincoln_Memorial
University of Maryland http://www.geol.umd.edu/courses/geol110/NationalMallGeology.pdf
National Park Service http://nature.nps.gov/geology/parks/