http://www.ftp2share.com/file/4093/Adventure Guide to Puerto Rico 4th Edition.html
The main island of Puerto Rico is about 100 miles long and 35 miles
wide, roughly the size of Yellowstone Park or the state of Delaware. It’s the farthest
east of the four major islands that form the Greater Antilles, which includes Cuba,
Jamaica and Hispaniola (Haiti and Dominican Republic). In terms of geologic time, the Caribbean islands are relatively young. A mere 200 million years ago, as dinosaurs roamed the super-continents, the tectonic plates of North and South America separated, and a rectangular chunk of the east Pacific plate – now known as the Caribbean
plate – knotted itself between them. Over the epochs, the Caribbean
plate began to shift north, creating pressure zones in the Puerto Rican Trench, which, at
28,000 feet, is the deepest spot in the Atlantic Ocean. The result was a series of violent volcanic eruptions depositing heaps of magma and ash over the ocean floor. Puerto Rico emerged from the sea about 135 million years ago. Ensuing tectonic motion folded piles of debris into the mountains of the Cordillera Central, which forms about 60% of Puerto Rico’s land mass and runs like a spine from the rain forest of El Yunque to the hills of Rincón. Due to heavy rainfall, most of the mountain range is thick with vegetation, including El Yunque, the only rain forest in US territory. At its most dramatic, the Cordillera
Central rises sharply into jagged peaks that would exceed Mt. Everest
in height, if measured from the ocean floor. From sea level, Puerto
Rico’s highest peak – Cerro de Punta – measures 4,389 feet.