I love EarthCaches and I particulary love Limestone. I couldn't believe the quality of Limestone I found in Miami on a recent holiday. The Limestone is so Fossil rich. I felt that I must put an Earthcache out here. The listed coords are for a Limestone bench which is full of fossils. Please read the text below, study the bench, research a little and then answer the questions below.
What is Limestone?
Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such as coral, forams and mollusca. Its major components are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3).
About 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to amazing landscapes. This is caused by rain/ sea water eroding the limestone over thousands to millions of years. Most cave systems are through limestone bedrock.
Miami Limestone
Miami Limestone (often referred to as the Miami Oolite), named by Sanford (1909), occurs at or near the surface in the southeastern peninsular of Florida, from Palm Beach County to Dade and Monroe Counties. It forms the Atlantic Coastal Ridge and extends beneath the Everglades where it is commonly covered by thin organic and freshwater sediments. The Miami Limestone occurs on the mainland and in the southern Florida Keys from Big Pine Key to the Marquesas Keys. From Big Pine Key to the mainland, the Miami Limestone is replaced by the Key Largo Limestone. To the north, in Palm Beach County, the Miami Limestone grades laterally northward into the Anastasia Formation. The Miami Limestone consists of two facies, an oolitic facies and a bryozoan facies. The oolitic facies consists of white to orangish gray, poorly to moderately indurated, sandy, oolitic limestone (grainstone) with scattered concentrations of fossils. The bryozoan facies consists of white to orangish gray, poorly to well indurated, sandy, fossiliferous limestone (grainstone and packstone). Beds of quartz sand are also present as unindurated sediments and indurated limey sandstones. Fossils present include mollusks, bryozoans, and corals. Molds and casts of fossils are common. The highly porous and permeable Miami Limestone forms much of the Biscayne Aquifer of the surficial aquifer system.
Limestone Fossils
To claim this cache:
Please answer the questions below and either message or email me the answers. You can log your find immediately. I will contact you if I feel that your answers are poor.
1. What are the dimensions of the Limestone bench at GZ in feet.
2. Describe the colour and texture of the bench.
3. What type of rock is Limestone?
4. What are the two main minerals in Limestone?
5. There are two main coral fossil types in the bench. What are the common names for these type of fossil?
6. (Optional) Please take a photo of yourself with or without your GPS at GZ - not giving away answers to the questions.
Reference Sources:
Kansas Geology Society. KGS Bulletin 169
wikipedia - Florida reef
Florida Museum of Natural history
Geology.com
Florida Atlantic University: Virtual field trip of Selected exposure of Miami Limestone