Geology [Atlas : Remains To Be Seen]

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====== Geology ======

{{::bogota_geology_map.jpg?600|}}

//// //Geology Map of Bogota Columbia (Helmens & van der Hammen, 1994//)////

{{:bogota_elevation_map.jpg?600|}}

//// //Elevation Map of Bogota Columbia (Helmens & van der Hammen, 1994//)////



The foundation of modern Bogotá was laid by a major tectonic uplift between approximately 5 and 3 million years ago, which raised the area by some 2000 metres, transforming it from a lower tropical landscape to a [[02|high-Andean environment]] (Helmens & van der Hammen, 1994). This upheaval was accompanied by the formation of a large tectonic basin, the Sabana de Bogotá, which began to fill with sediments around 3.5 million years ago (Helmens & van der Hammen, 1994). The eastern boundary of this basin is defined by the prominent Monserrate-Guadalupe scarp, which Clements (1940) identified as the result of an overthrust fault, the Bogotá Fault, where older Cretaceous rocks were thrust over younger probable Tertiary beds. This structural history created the large, flat plain upon which the city is built.

The infilling of this basin with hundreds of metres of lacustrine (lake) and fluvial (river) sediments throughout the Pliocene and Quaternary periods has been critical for the region's agriculture. These sediments are the parent material for the deep, fertile soils of the Sabana, which have supported human settlement for millennia. Furthermore, the sediment record reveals a history of volcanic activity, with numerous tephra (volcanic ash) layers intercalated within the sequence (Helmens & van der Hammen, 1994). These ash deposits contribute essential minerals, enhancing the fertility of the [[26|soils]] that are crucial for agriculture in the region.

Perhaps the most critical geological component for Bogotá is the [[18|páramo,]] the high-altitude alpine ecosystem. The geological studies show that the Quaternary period, starting around 2.4 million years ago, was marked by repeated glacial-interglacial cycles (Helmens & van der Hammen, 1994). During cold glacial periods, glaciers formed on the highest peaks, and the tree line descended, allowing open páramo vegetation, dominated by grasses, to expand. This vegetation is a phenomenal water regulator. The research indicates that fluctuations in the lake level of the ancient Bogotá lake were influenced by differences in evaporation and, crucially, by the water interception and storage capacity of forest versus open páramo vegetation (Helmens & van der Hammen, 1994). The páramo's sponge-like function is therefore a direct result of the climatic conditions shaped by the region's geological uplift, and it is the primary source of freshwater for Bogotá's millions of inhabitants.

In conclusion, the geology of the Andean region is not merely a backdrop for Bogotá but is fundamental to its very existence. The tectonic forces created the habitable plain and the surrounding water-catching mountains, the sedimentary history provided the fertile soils, and the Quaternary climatic fluctuations, recorded in the geological strata, forged the páramo ecosystems that are vital for the city's water security.

__Bibliography__

Clements, T. (1940) //‘The Bogota Fault, Colombia, South America’//, The Journal of Geology, 48(6), pp. 660–669. Available at: [[https://www.jstor.org/stable/30058704 (Accessed: 20 November 2025).]]

Helmens, K.F. & van der Hammen, T. (1994) //‘The Pliocene and Quaternary of the high plain of Bogotá// (Colombia): a history of tectonic uplift, basin development and climatic change’, Quaternary International, 21, pp. 41–61. Available at: [[https://www.sciencedirect.com/science/article/pii/1040618294900205]] (Accessed: 20 November 2025).