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Coquina Outcrop EarthCache

Hidden : 05/06/2008
3 out of 5
1.5 out of 5

Size: Size:   not chosen (not chosen)

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Geocache Description:

Earthcache is located on Kure Beach and can only be accessed at low tide, which is the reason for the high difficulty.


Southeastern North Carolina is home to a unique geological formation and it is the only natural rocky shoreline in NC.  The coast near Fort Fisher, is host to a hard rock outcropping of coquina rock that is rare and distinctive.

What exactly is coquina rock, and what makes it so special?

Coquina is a sedimentary rock that is cemented together by seashells or coral, giving it a rough, gravelly look and feel. Because shells are made of calcium carbonate, coquina is formally a limestone. Coquina is the Spanish word for cockleshells or shellfish. Coquina forms near shore, where wave action is vigorous and sorts the sediments well. Notice that the pieces are all broken and rounded by the abrasion of the waves. Experts disagree on just how long ago the rock was created, but it’s a relatively young formation, with estimates of its origin ranging from 12,000 to 80,000 years ago.  The rock was used in years past as a building material for homes and even forts, because it was good at absorbing cannon fire.

The coquina outcrop extends out into the Atlantic ocean to the continental shelf. Islands such as Kure Beach, NC are constantly changing. Offshore currents carry sand away from one end of the island and deposit it at the other end, thereby changing the shape of the island. The coquina outcrop’s extension into the ocean acts as a natural jetty, which changes the way the sand moves.

This tidal zone is continually shaped by the actions of sun, wind, water, and rock. The rocky areas on the edge of the ocean that are filled with sea water at low tide create tide pools. The tide pools in the outcropping plays host to a large array of sea life, such as sea stars, horseshoe crabs, whelks, sea urchins, clams, conchs, and hermit crabs. Life is tough for plants and animals that live in tide pools. Here portions of the shoreline are regularly covered and uncovered by the advance and retreat of the tides. In order to survive, tide pool life forms must avoid being washed away by the tidal waves, keep from drying out in the sunlight of low tide, and avoid being eaten.

The tide pools are a unique and brutal habitat where the ocean meets the land. The sun bears down, heating exposed surfaces and organisms. Winds blow and contribute to the wave action, erosion, and drying of exposed plants and animals. Water in the form of waves endlessly pound at the rocks, constantly reshaping the coastline. Rocks are pounded by the waves and loose stones and sand grind into the shoreline.

To log this Earthcache, you need to visit at low tide! Look for the Ft. Fisher tide!!!

Requirements for logging: 

1. Must either send me an email answering the following:

a) How do you think this coquina rock outcrop affects sand movements on the nearby beaches?

b)What animals did you see on the coquina outcrop?

c) Send me the coordinates of where the low tide was when you were there.

2. Or take a picture of you with the outcrop in the background.

Additional Hints (No hints available.)