The Atlantic Coastal Ridge - Earthcache EarthCache
The Atlantic Coastal Ridge - Earthcache
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At the posted coordinates (red arrow), you will have the rare opportunity to see and interact with the Atlantic Coastal Ridge from sea-level to ground level. We selected this location because parking is easy, it is a serene and scenic area, and you are able to note the difference in elevation between the canal (sea-level) and the top of the limestone ridge.
Atlantic Coastal Ridge Map
The Limestone The Miami Limestone, formerly known as the Miami Oolite, is one of three distinct Pleistocene rock formations in southeastern Florida. The formation was deposited during the Sangamon interglacial and Wisconsin glacial stages as a narrow band of oolitic carbonate in a north-south trending barrier bar system along the eastern portion of the area now known as Miami-Dade and Broward counties. Miami Limestone is about 130,000 years old. The formation has two distinct facies; the eastern oolitic facies that forms the Atlantic Coastal Ridge, and the bryozoan facies to the west, in the Everglades. The Miami Limestone is one of three deposits in South Florida; with the Anastasia Formation to the north, and the Key Largo Limestone to the south.
Looking North From GZ
The Ridge The Atlantic Coastal Ridge which runs from Mahogany Hammock northeast to Miami (see map above) was formed as longshore currents pushed ooids up into a long ridge. Ooids are small (2 mm in diameter), spheroidal, coated (layered) sedimentary grains, usually composed of sand and calcium carbonate. The ooids later cemented into the multi-layered sedimentary rock known as Miami Oolite (Miami Limestone). Cross-bedding is typical of sedimentary structures, and is defined as horizontal units that are composed of visible inclined layers. The Cocoplum Area, where this Earthcache is located along the Atlantic Coastal Ridge, can be as much as 30 feet above sea-level. The ridge continues south through an area known as Cutler Ridge (so named because it is perched atop the ridge).
Looking North From VIEW Waypoint
Earthcache Site Parking is available within 30 feet of GZ. Please make your way down to the lower level through the entryway about 50 feet west of the benches. At the posted coordinates on the lower level, you will note that the limestone has been cut by man's machines to create this canal. You are able to closely view the formation, and the sedimentary layers that make up the Miami Limestone. The thickness of the limestone ridge can be very easily seen from this location.
Completing the Earthcache To get credit for completing this Earthcache, please send your answers to the following questions to our profile Email. Incorrect answers may lead to further questions from us, or deletion of your find log. You may log your find after you have transmitted your answers. Photos are optional. However, photos of you or your GPS at GZ are always welcome.
1. From the lower level, please locate the limestone wall at GZ. How thick is each horizontal sediment layer that you can see? Measure in inches or parts of an inch (cm or mm is OK too)
2. Is cross-bedding visible along the limestone wall? Yes/No
3. Touch the limestone layers. Is the material shiny and smooth or is it sharp and grainy?
4. While standing at the lower level at GZ, can you estimate the distance in feet from the water level below you to the parking area above you?
Optional task, but worth taking a few more minutes to check out. At the VIEW Waypoint provided (N 25 42.335, W 080 15.623), you can also view the canal and the cut out section of the canal and the maximum height of the limestone ridge at this location. Manatees and iguanas can sometimes be spotted in this area.
Portions of the information included in this earthcache were gleaned from the following public references: Duke.edu, Wikipedia, National Park Service, FAU Geology.
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