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Origins
Coquina rock formed during a period dating from approximately 1.8 million to 11,500 years ago, known as the Pleistocene Ice Age. It developed from shelled animal life that was abundant in the oceans before this ice age. In the U.S., it exists in Florida and North Carolina. The color and consistency of the rock varies according to the differing proportions and types of sand and other components. In Florida, it exists as far as 20 miles inland.
Uses
Coquina rock has many uses. It is very decorative and appears in many forms in Florida, enhancing the visual appearance of a variety of outdoor structures. Gardeners use it to create landscaping features such as waterfalls and the edging around ponds and garden beds. In buildings, it makes an attractive veneer on chimneys, fireplaces and gated entrances. Coquina rock also forms the structural material for monuments, sea walls and retaining buffers.
History
The history of coquina rock in Florida stretches back over 400 years. The most famous use of it is in the walls of the Castillo de San Marcos in St. Augustine. Coquina rock was a good choice because of its soft quality. This meant that cannonballs did not shatter the stone. Instead, they sank into it, doing no major damage to the main structure of the fort. Miners also extracted the stone for its phosphate, which is a fertilizer.
Other Sedimentary Rocks
Other sedimentary rocks include sandstone, shale, coal, rock salt and limestone. Sandstone and shale are the result of ages of weathering of sand and clay. Rock salt and some types of limestone formed out of chemical solutions of minerals. For example, rock salt comes from ocean or salt lakes that have evaporated. Coal and other kinds of limestone formed from the accumulation of organic matter such as plant debris and shells. Coal is most often originally material from swamps.