Named for the explorer Christopher Columbus, (but more often associated with drugs than Columbus) Colombia is a large and physically diverse nation. It is the fourth-largest country in South America (after Brazil, Argentina, and Peru), with an area seven times greater than that of New England and almost twice that of France. Its vast territory is one of great physical contrasts, ranging from the towering, snowcapped peaks of the Andes to the hot, humid plains of the Amazon River Basin.
Not only is Colombia large in area, but it also has a large population, containing more people than any other South American country except Brazil. The nation's population is not evenly distributed. Most of the people live in the mountainous western third of the country, where Bogota, the capital, and most of Colombia's other large cities are located. Because this western region has a pleasant climate and rich soil, it is also where most agricultural activity takes place.
Colombia has more physical diversity packed into its borders than any other area of comparable size in Latin America. The country is part of the Pacific "Ring of Fire," a region of the world characterized by frequent earthquakes and volcanic eruptions.
Colombian surface features form complicated patterns. The western third of the country is the most complex. Starting at the shore of the Pacific Ocean in the west and moving eastward at latitude of 5 degrees north, a diverse sequence of features is encountered. In the extreme west are the very narrow and discontinuous Pacific coastal lowlands, which are backed by the Serrama de Baudo, the lowest and narrowest of Colombia's mountain ranges. Next is the broad region of the Rfo Atrato/Rfo San Juan lowland, which has been proposed as a possible alternate to the Panama Canal as a human-made route between the Atlantic and the Pacific oceans.
The chief western mountain range, the Cordillera Occidental, is a moderately high range with peaks reaching up to about 13,000 ft. (4,000 m.). The Cauca River Valley, an important agricultural region with several large cities on its borders, separates the Cordillera Occidental from the massive Cordillera Central. Several snow-clad volcanoes in the Cordillera Central have summits that rise above 18,000 ft. (5,500 m.). The valley of the slow-flowing and muddy Magdalena River, a major transportation artery, separates the Cordillera Central from the main eastern range, the Cordillera Oriental. The peaks of the Cordillera Oriental are moderately high. This range differs from Colombia's other mountain ranges in that it contains several large basins.
In the east, the sparsely populated, flat to gently rolling eastern lowlands called llanos cover almost 60 percent of the country's total land area.
This cross section of the republic does not include two of Colombia's regions: the Caribbean coastal lowlands and the Sierra Nevada de Santa Marta, both in the northern part of the country. The lowlands in the west are mostly swampy; the reed-filled marshes of the area are called cienagas by the people of Colombia. The Guajira Peninsula in the east is semiarid. The Sierra Nevada is a spectacular triangular snowcapped block of rock that towers over the eastern part of this lowland.
Climate - Colombia's proximity to the equator influences its climates. The lowland areas are continuously hot. Altitude affects temperature greatly. Temperatures decrease about 3.5° F. (2° C.) for every 1,000-ft. (300-m.) increase in altitude above sea level.
Rainfall varies by location in Colombia, tending to increase as one travels southward. This is especially true in the eastern lowlands. For example, rainfall in parts of the Guajira Peninsula seldom exceeds 30 in. (75 cm.) per year. Colombia's rainy southeast, however, is often drenched by more than 200 in. (500 cm.) of rain per year. Rainfall in most of the rest of the country runs between these two extremes.