Rocky Shores of Princess Cays – Bahamian Carbonate EarthCache

On a recent visit to Princess Cays I went for a walk along the beautiful sandy beach there and before long I ran out of the sandy beach and found myself walking a rocky shoreline.  A little investigation and research later and I had an idea for this earthcache.

Princess Cays actually sits on the southern tip of Eleuthera, which is part of the Bahamian archipelago. Unlike volcanic islands, the Bahamas are built almost entirely from carbonate sediments—materials produced by marine organisms and shaped by wind, waves, and chemical processes.

Along the rocky sections of the shoreline near Princess Cays, visitors can observe exposed limestone, solution features, and wave-cut notches. These formations allow you to explore how tropical carbonate coastlines evolve and what natural processes shape them.

This EarthCache highlights:

• Bahamian oolitic and biogenic limestone

• Karst features formed by dissolution

• Marine erosion shaping the coastal rock

• The transition between sandy beaches and rocky platforms

Background Information of this area:

1. Bahamian Carbonate Platform

The Bahamas rest on a massive carbonate bank. Unlike continents formed from igneous and metamorphic rocks, Bahamian rocks originate from calcium carbonate (CaCO₃) precipitation and biological activity—coral, shell fragments, algae, and tiny grains called oolites.

2. Bahamian Limestone

Typical limestone types you may see here include:

• Oolitic limestone – a type of sedimentary rock composed of small, spherical grains called ooids. These ooids, which are made of calcium carbonate, form in warm, shallow, marine environments as layers of carbonate precipitate around a nucleus, such as a sand grain, in high-energy water. Once lithified (cemented together), they form a distinct clastic rock often used in construction.

• Bioclastic limestone – a sedimentary rock composed primarily of fragments of marine organisms like shells, corals, and algae. These fragments, called bioclasts, accumulate on the seafloor, and over time, they are cemented together by precipitated calcium carbonate, forming a rock that often contains recognizable fossils. Examples include coquina, which is made mostly of whole shells, and other types formed from smaller fossil debris. 

• Eolianite – windblown sand dunes that later lithified into rock. Much of Eleuthera’s coastal rock is ancient dune rock.

3. Coastal Erosion Features

As waves repeatedly strike this coast, they carve distinctive features:

• Wave-cut platforms – flat surfaces created at sea level.

• Notches – indentations where waves force saltwater into cracks.

• Karst solution holes – pits where slightly acidic rainwater dissolved the rock.

These features help geologists estimate sea-level changes and coastal stability.

What to Observe & Questions to Answer:

To log your visit you must provide the following observations and answers (submit via email or messaging via geocaching.com):

1. Examine the limestone surface. Describe the texture:  Are the grains fine or coarse?  Do you see any ooids (very small, spherical grains) or larger shell fragments?  Is the rock smooth, jagged, pitted, or layered?

2. Has this area been affected by erosion? If so what likely caused the erosion? Briefly describe what does the area looks like?

3. Based on the description and what you see, what type of rock does this appear to look more like?:  Oolitic limestone, Bioclastic (shell-rich) limestone, or Eolianite (lithified dune rock)

4. (REQUIRED] In accordance with the updated guidelines from Geocaching Headquarters published in June 2019, photos are now an acceptable logging requirement and WILL BE REQUIRED TO LOG THIS CACHE. Please post a photo in your log of yourself or a personal item at GZ or with your cruise ship in the background.