Puerto Rico - Geography

Geography

Puerto Rico consists of the main island of Puerto Rico and various smaller islands, including Vieques, Culebra, Mona, Desecheo, and Caja de Muertos. Of these last five, only Culebra and Vieques are inhabited year-round. Mona is uninhabited most of the year except for employees of the Puerto Rico Department of Natural Resources. There are also many other even smaller islands including Monito and "La Isleta de San Juan" which includes Old San Juan and Puerta de Tierra and is connected to the main island by bridges.

The Commonwealth of Puerto Rico has an area of 13,790 square kilometers (5,320 sq mi), of which 8,870 km2 (3,420 sq mi) is land and 4,921 km2 (1,900 sq mi) is water. The maximum length of the main island from east to west is 180 km (110 mi), and the maximum width from north to south is 65 km (40 mi). Puerto Rico is the smallest of the Greater Antilles. It is 80% of the size of Jamaica, just over 18% of the size of Hispaniola and 8% of the size of Cuba, the largest of the Greater Antilles.

Puerto Rico is mostly mountainous with large coastal areas in the north and south. The main mountain range is called "La Cordillera Central" (The Central Range). The highest elevation in Puerto Rico, Cerro de Punta 1,339 meters (4,393 ft), is located in this range. Another important peak is El Yunque, one of the highest in the Sierra de Luquillo at the El Yunque National Forest, with an elevation of 1,065 m (3,494 ft).

Puerto Rico has 17 lakes, all man-made, and more than 50 rivers, most originating in the Cordillera Central. Rivers in the northern region of the island are typically longer and of higher water flow rates than those of the south, since the south receives less rain than the central and northern regions.

Puerto Rico is composed of Cretaceous to Eocene volcanic and plutonic rocks, overlain by younger Oligocene and more recent carbonates and other sedimentary rocks. Most of the caverns and karst topography on the island occurs in the northern region in the carbonates. The oldest rocks are approximately 190 million years old (Jurassic) and are located at Sierra Bermeja in the southwest part of the island. They may represent part of the oceanic crust and are believed to come from the Pacific Ocean realm.

Puerto Rico lies at the boundary between the Caribbean and North American plates and is being deformed by the tectonic stresses caused by their interaction. These stresses may cause earthquakes and tsunamis. These seismic events, along with landslides, represent some of the most dangerous geologic hazards in the island and in the northeastern Caribbean. The most recent major earthquake occurred on October 11, 1918, and had an estimated magnitude of 7.5 on the Richter scale. It originated off the coast of Aguadilla and was accompanied by a tsunami.

The Puerto Rico Trench, the largest and deepest trench in the Atlantic, is located about 115 km (71 mi) north of Puerto Rico at the boundary between the Caribbean and North American plates. It is 280 km (170 mi) long. At its deepest point, named the Milwaukee Deep, it is almost 8,400 m (27,600 ft) deep, or about 5.2 miles.

Located in the tropics, Puerto Rico has an average temperature of 82.4 °F (28 °C) throughout the year, with an average minimum temperature of 66.9 °F (19 °C) and maximum of 85.4 °F (30 °C). Temperatures do not change drastically throughout the seasons. The temperature in the south is usually a few degrees higher than the north and temperatures in the central interior mountains are always cooler than the rest of the island. The hurricane season spans from June to November. The all-time low in Puerto Rico has been 39 °F (4 °C), registered in Aibonito. The average yearly precipitation is 1687mm.

Species endemic to the archipelago are 239 plants, 16 birds and 39 amphibians/reptiles, recognized as of 1998. Most of these (234, 12 and 33 respectively) are found on the main island. The most recognizable endemic species and a symbol of Puerto Rican pride is the Coquí, a small frog easily identified by the sound of its call, and from which it gets its name. Most Coquí species (13 of 17) live in the El Yunque National Forest, a tropical rainforest in the northeast of the island previously known as the Caribbean National Forest. El Yunque is home to more than 240 plants, 26 of which are endemic to the island. It is also home to 50 bird species, including the critically endangered Puerto Rican Amazon. Across the island in the southwest, the 40 km2 (15 sq mi) of dry land at the Guánica Commonwealth Forest Reserve contain over 600 uncommon species of plants and animals, including 48 endangered species and 16 endemic to Puerto Rico.