71. Coquina Rocks (Washington Oaks Gardens State Park)

Geology of the Coquina Rocks

https://www.floridastateparks.org/learn/geology-coquina-rocks 

The second largest outcropping of Coquina rock is found here, giving visitors a glance back at geologic time. Coquina rock is a type of sedimentary rock (specifically limestone), formed by the deposition and subsequent cementation of mineral or organic particles on the floor of oceans or other bodies of water at the Earth's surface. In other words, the rock is formed by the accumulation of sediments.

The Coquina rocks at Washington Oaks is part of the Anastasia formation, which stretches from St. Augustine to Palm Beach County, and was created during the Pleistocene era (12,000 - 2.5 million years ago). During that era when sea level was lower, shells and sand were exposed to rain. The slightly acidic rainwater dissolved some of the calcium carbonate in the shells, which “glued” together the sand and shells into rock. If you look closely at the rock, you can see millions of the individual shells and sand cemented together.