Central America

I

Introduction

Central America, region of the western hemisphere, made up of a long, tapering isthmus that forms a bridge between North and South America. Central America, which is defined by geographers as part of North America, has an area of about 523,000 sq km (201,930 sq mi) and includes the countries of Guatemala, Belize, El Salvador, Honduras, Nicaragua, Costa Rica, and Panama. The region has a population of approximately 40.2 million (2004).

II

The Natural Environment

In strictly geological terms, Central America begins at the narrow Isthmus of Tehuantepec in southern Mexico. That narrow section divides the volcanic rocks to the north-west from the folded and faulted structures of Central America. The southernmost geological limit of Central America is the Atrato river valley, in Colombia, South America, just east of the Panama border.

A

Geological History

Central America, a particularly unstable region of the Earth's crust, is on the western edge of the Caribbean plate (see Plate Tectonics). Subduction of oceanic crust beneath this edge, beginning in the Miocene epoch, about 25 million years ago, has lifted the land from the sea. In the earliest stage, a peninsula and archipelago formed. Later, about 3 million years ago, the scattered islands coalesced to form a true land bridge, or isthmus, linking North and South America.

Keeping pace with subduction and uplift have been volcanic eruptions—Central America has at least 14 active volcanoes—and frequent earthquakes. In the 20th century Managua, the capital of Nicaragua, was twice destroyed by earthquakes. The most recent, in 1972, took 10,000 lives. Volcanic activity has produced a landscape dotted with majestic cones built from eruptions of ash and lava, and beautiful lakes formed in collapsed volcanic craters (calderas). In October 2005 a tropical storm hit Central America causing devastation and triggering mudslides in Guatemala that killed around 1,000 villagers.

B

Physiographical Regions

For the most part Central America is a rugged, mountainous area, with 109 large volcanoes, some more than 4,000 m (13,120 ft) high, although most are dormant; Tajumulco, in Guatemala, is the highest at 4,220 m (13,845 ft). Central America is one of the most active volcanic zones in the western hemisphere. The land surface slopes up rather abruptly from a narrow coastal plain along the Pacific Ocean to the mountain crests and then descends more gradually to a broader plain along the Caribbean Sea. Two major interoceanic passes cut through the highlands of Central America, one in Nicaragua (from the mouth of the San Juan River to Lake Nicaragua) and the other in Panama (along the route of the Panama Canal). The Pacific coastline is about 2,830 km (1,760 mi) long, and the Caribbean coastline is approximately 2,740 km (1,700 mi) long. Several groups of small islands lie off the Caribbean coast, and some of them, such as the Islas de la Bahía in the Gulf of Honduras, are inhabited.