Destination Key Largo Guide

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Limestone! What are the Florida Keys Made From?

The Florida Keys are a chain of limestone islands that extend from the southern tip of the Florida mainland southwest to the Dry Tortugas, a distance of approximately 220 miles. They are island remnants of ancient coral reefs (Upper Keys) and sand bars (Lower Keys) that flourished during a period of higher sea levels approxi mately 125,000 years ago (a period of geologic time known as the Pleistocene Epoch). During the last ice age (100,000 years ago) sea level dropped, exposing the ancient coral reefs and sand bars which became fossilized over time to

form the rock that makes up the island chain today. The two dominate rock formations in the Keys are Key Largo Limestone and Miami Oolite. During this time of lower sea levels, the Florida land mass was much larger than it is today and the area now referred to as Florida Bay was forested. As glaciers and polar ice caps started melting 15,000 years ago, flooding of land combined with tidal influence changed the geography of the Keys and their surrounding areas.

Credit: Florida Keys Marine Sanctuary NOAA

Destination Key Largo


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