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Gigapans

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  1. The Rocky Islands are exposures of Proterozoic-age metagraywacke of the Mather Gorge Formation. Graywacke is a "dirty" sandstone deposited by turbidity currents in submarine fans (a.k.a. "abyssal fans"), which are essentially big piles of sediment in deep ocean basins. This is likely the original enviro...

  2. The Rocky Islands are exposures of Proterozoic-age metagraywacke of the Mather Gorge Formation. Graywacke is a "dirty" sandstone deposited by turbidity currents in submarine fans (a.k.a. "abyssal fans"), which are essentially big piles of sediment in deep ocean basins. This is likely the original environment where t...

  3. As North America collided with the Chopawamsic Terrane during the Taconian orogeny, temperatures within the crust started to rise. As things got warmer, partial melting occured. Minerals present in the graywacke that had low melting temperatures, like quartz, potassium feldspar, and muscovite mica (felsic minerals) all...

  4. A geologist explains some of the rock formations at Northwest Branch Creek here: nvcc.edu/home/cbentley/geoblog/2008/08/geological-excursion-in-silver-spring.html Will open in a new tab or window

  5. To learn more about this, the largest sub-watershed of the Anacostia River, see: www.neighborsnwb.org Will open in a new tab or window/

  6. For more about the "Northwest Branch Stream Valley Park Unit 3," see: www.mc-mncppc.org/Parks/park_of_the_day/nov/parkday_nov10.shtm Will open in a new tab or window