Geology of Colombia refers to thegeological composition of the Republic ofColombia that determines itsgeography. Most of the emerged territory of Colombia covers vast areas within theSouth American Plate, whereas much submerged territory lies within theCaribbean Plate and theNazca Plate.

As in the rest of South America, a combination of external and internal tectonic, volcanic, and glacial forces over the eons formed Colombia's present-day geology.^[1] Island-like outcrops ofmetamorphic rocks in the easternLlanos are visible remnants ofPrecambrian times. During the 289-million-year-longPaleozoic Era, which began 539 million years ago, the ocean invaded the area which is exposed in Colombia'sAndean zone, as subterraneanvolcanic eruptions in the western part of the country spouted lava.^[1] In theTriassic Period of the 186-million-year-longMesozoic Era, which began 252 million years ago, the sea that occupied the Andean zone separated into two parts after theCordillera Central rose.^[1] Large layers ofsedimentary rock were deposited during theJurassic Period, which ended with greatigneous activity.^[1] During theCretaceous Period, the sea to the east of the Cordillera Central extended toPutumayo region in the south, while subterranean volcanic activity continued to the west of the Cordillera Central.^[1] During theCenozoic Era, which began about 66 million years ago, the seas withdrew from most of Colombia's territory, and enormousgranite masses formed along theCordillera Occidental.^[1] The three cordilleras began to take shape 12 million years ago.^[1] The Cordillera Occidental and the Cordillera Central form the western and eastern sides of a massive crystalline arch, which extends from the Caribbean lowlands to the southern border of Ecuador.^[1] The Cordillera Oriental, however, is composed of folded stratified rocks overlying a crystalline core.^[1]

Tectonic movement of the cordilleras continues today, as evidenced by frequentseismic activity.^[1] Indeed, Colombia remains part of thePacific Ring of Fire, an active seismic area that surrounds thePacific basin.^[1] The country is located where threelithospheric plates—Nazca, Caribbean, and South American—converge, and their movement produces different types of geologicfaults.^[1] Almost all of the country's many earthquakes in recent centuries have occurred in the mountainous and coastal regions.^[1] Recent major earthquakes include those inPopayán on March 31, 1983, andin the nation's coffee-growing belt on January 25, 1999; and one on March 6, 1987, on the border withEcuador, measuring 7.0 on theRichter magnitude scale.^[1] Recent earthquakes that struck Colombia's Pacific coast areas have included one accompanied by atsunami inTumaco,Nariño Department, on December 12, 1979, measuring 7.9 on the Richter magnitude scale, the largest in northwestern South America since 1942; another on November 15, 2004, with a magnitude of 6.7; and one on September 10, 2007, measuring 6.8.^[1] Although construction standards are high for new buildings in the main cities, smaller cities and rural zones are particularly vulnerable to earthquakes.^[1]

Colombia is formed by two great territorial zones, one submerged in thePacific Ocean and theCaribbean Sea covering a total area of 828,660 km² and the second is the emerged land which is formed by theAndes mountain range and theLlanos plains that are shared withVenezuela and cover an area of some 1'143,748 km².

In the emerged zone the region is washed by numerous rivers that include theMeta,Vichada and theInirida rivers which contribute to other major rivers like theOrinoco River,Vaupés River,Caquetá River,Putumayo River andApaporis River. This Llanos region is also divided into three subregions;

The northern area characterized by its wavy plains similar to a savanna and located between theAndes mountain range and theGuiana Shield formed during theTertiary mostly covered with sand and clay, while the rivers contributed with sedimentary elements from the Andes during theQuaternary.

The second region is located in the central area of the Llanos with a more wavy topography and formations elevated like theAlto del Vaupés or theSerranía de la Macarena mountain range, isolated in the middle of the plains and towards theGuyana Shield.

The southern area is made up by most of the Putumayo andAmazon River basins, while the topography is flatter than the other two regions, this area is covered by densejungle and makes up most of theAmazon Region of Colombia.

TheAndean Region of Colombia is the other emerged area of the two areas that compose the geology of Colombia. This area originated after a complex geological development that started in thePaleozoic era when theNazca Plate collapsed with theSouth American Plate pushing it under theCaribbean Plate that created volcanic islands off the Pacific coast off Colombia and theisthmus of Panama. TheColombian Massif, near the border withEcuador formed and split into three mountain ranges:Cordillera Central (central mountain range),Cordillera Oriental (Eastern mountain range) and theCordillera Occidental (Western mountain range), each product of three different formation processes and divided from one another by valleys.

The Cordillera Oriental was the most recently formed mountain range of the three, developing by the end of theTertiary period and consisting mostly of sedimentary elements. The formation of the Cordillera Oriental covered the continental platform withpelagic sediments withPrecambrian andPaleozoic metamorphic rocks bases. The area of theBogotá Savanna and the highland ofCundinamarca andBoyacá tableland. To the northeast the volcanic metamorphic formed massif inSantander andNorte de Santander formed the Andes in Venezuela and the mountain ranges ofPerijá andMotilones, between the border of Colombia and Venezuela during the Pleistocene and added sedimentary rocks during the Mesozoic.

The Cordillera Central formed from theGuyana shield during the Paleozoic era with intrusions from granite and metamorphism. To the west presents basic volcanic rocks from the end of the Cretaceous period anddioriteintrusive rocks from the Tertiary. To the west there are metamorphic Paleozoic rocks and two major massifs inIbagué and theSerranía de San Lucas. Another important formation is theBaudó Mountains to the west of the country.

• Natural Regions of Colombia
• Geography of Colombia
• List of volcanoes in Colombia

• (in Spanish)Colombian Institute of Geology and Mining

• Geology of Colombia

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• Articles with Spanish-language sources (es)