This Island feels the pulse of the Sea EarthCache
This Island feels the pulse of the Sea
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This is not a typical Geocache. There is no container to find and no physical log to sign at the coordinates. Instead you will be able to enjoy and learn about an important geological feature of Washington, D.C. It is located on Theodore Roosevelt Island and can only be accessed by a footbridge from parking off the George Washington Memorial Parkway.
Please stay on the trails at all times. As per park rules, do not leave, take, mark, dig, disturb, or post anything in the park.
Take a walking tour of Roosevelt Island and learn about its geological features at three stops along the way. There will be a question to be answered about the island's bedrock, take careful note of the environment at the swamp, and then you will compare swamp and marsh at the final destination.
First Stop: Bedrock
The Potomac River has failed to erode away this island because at its core is a very hard bedrock of mica schist. It began as very thin layers of mud transformed over millions of years into impermeable metamorphic rock. Minerals crystallize because of heat and pressure, and mica schist has fairly coarse grains that allow you to see some of that structure. Lining the walking path to the right of the sign is a long, roughly rectangular piece half buried in the soil--you don't need to leave the path to see it. A few quartz crystals really stand out--how big and what color is the largest one on its face?
Second Stop: Swamp
As the Potomac River flows past, it deposits sediments along the shores that build up to form natural levees, meaning poor drainage for the island. Swamps are wetlands because of their saturated soils. Take a look around at the swamp in this vicinity and take note of the water, soil, and vegetation
Third Stop: Tidal Marsh
Marshes are open areas that are always covered by water. The rise and fall of water in tidal marshes in river estuaries are created by ocean tides, yet this marsh is far enough away from the sea that salt water does not enter. Brackish marshes support only a few kinds of wiry grasses that can tolerate salt from the ocean, while freshwater varieties support a much greater variety of plant life. Take a look around and compare the marsh to the swamp---what is different about the water and the general area? What signs of the ebb and flow of tides are left behind for you to see? The sign which provided the name for this cache tells you that this is a freshwater marsh, but what evidence around you convinces you of that fact?
Your last task is strictly optional: post a picture of you and/or your GPSr at the Marsh.
As per Earthcache rules, I must delete your log if you don't send me the answers to the questions above within 5 days of logging this cache. Thanks for visiting my Earthcache!
Permission to place this Earthcache has been granted by the National Park Service through the office of the George Washington Memorial Parkway.
Thanks to the Ohio Caching Crew (skibug9, n8lgp, and Tara16) for helping me place this cache on a fun and memorable trip to D.C.
**********Congrats to rockhoundbmw for FTF!!!************
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Treasures
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