GEOLOGICAL ORIGIN AND CHARACTERISTICS OF COSTA RICA
Central America is characterized more by its biodiversity than by the homogeneity that predominates in this region due to its geographical location. Furthermore, it boasts excellent features, including a dual climatic condition: one influenced by interoceanic currents and the other by intercontinental currents.
Structurally, the region extends from Mexico at the Isthmus of Tehuantepec to the Atrato Valley in Colombia, according to Dengo (1975). During this time, the nearly 3,000-kilometer-long interoceanic channel separated North America from South America. At this time, northern Central America was composed of invasive sedimentary rocks and, due to tectonic movements, it was already formed in the same way as before. When the Tertiary period ended, a channel approximately 300 km long still separated northern Nicaragua from northern Colombia. In the southern part of Central America, during the Early Tertiary and Late Cretaceous periods, it resembled a chain of volcanic islands. In the Pliocene, three to four million years ago, the land bridge formed and consolidated, separating the Pacific Ocean from the Atlantic Ocean and North America from South America.
Thanks to its position as a land bridge, Central America facilitated the exchange of animal and plant life, as well as human migrations and cultural exchange. The mountain ranges located in Guatemala, Honduras, and northern Nicaragua created isolation, which favored the evolution of endemic species and formed a barrier that prevented the spread of other species. A clear example of this is the pine tree, which is not found south of Lake Nicaragua.
South of Costa Rica lies the Talamanca Mountain Range, where North American oaks mingle with South American conifers. The combination of this great variety of North and South American species makes Central America a region privileged by its rich and diverse flora and fauna, a diversity unmatched anywhere else in the Western Hemisphere and beyond.
During the Pleistocene glacial period, the Bering Strait was possibly frozen, allowing migrations from Asia to the Americas. The first inhabitants, with a rudimentary culture dedicated to hunting, gathering, and fishing, spread throughout the continent. Gradually, two types of agriculture developed. One was based on the cultivation of tubers, such as cassava, in the Andean region.
In Mesoamerica, the crops were corn and beans. Thanks to this type of agriculture, three great civilizations of the Americas flourished: the Maya and Aztec in Mexico and Guatemala, and the Inca in Peru.
GEOLOGICAL HISTORY OF COSTA RICA
The geological history of our country began more than 200 million years ago. During this period, the continental landmasses were likely in a situation very similar to their current state.
As a result of the separation of the North American, European, and African plates, and as a consequence of the action of convection cells on magma, the Atlantic Ocean was created, its origin being due to an area of extension that stretches from Iceland to Antarctica.
The orogenic process (the process of mountain building, studied as a tectonic structural event) began with volcanic activity, accompanied by the formation of mid-ocean ridges and submarine mid-ocean ridges. One result of this process is an eastward-facing archipelago, later known as the outer arc, actually represented by a series of eroded mountain ranges located on the Nicoya Peninsula, Playa Herradura, the Osa Peninsula, and at Punta Burica.
Intense volcanic activity characterized this period, and as a result, erosion processes increased in the sedimentation of these areas. Around sixty million years ago, during the Early and Middle Eocene (a major division of the geological timescale and the second epoch of the Paleocene period in the Cenozoic era), almost the entire outer arc disappeared, including a cluster of islands known as the Guanarivas emergents.
During the Oligocene, 25 million years ago, these islands disappeared into the ocean and were covered by detritus material (matter of death), as a result of degradation and subsequent sedimentation.
Due to the intense volcanic activity that gave rise to Aguacate Mountain and the Talamanca mountain range, an ascent began, reaching the highest altitude of the inner arc. This volcanism would later give rise to the Central Volcanic Range and the Guanacaste Mountain Range.
Therefore, the formation of the territory that Costa Rica occupies today has taken approximately 8 to 10 million years, due to the fact that the geological structures are growing at a rate of 10 mm per year.
MAIN GEOLOGICAL STRUCTURES OF COSTA RICA:
The topography runs from northwest to southeast, with four mountain ranges: Guanacaste, Tilarán, Central Volcanic, and Talamanca.
The Guanacaste Volcanic Mountain Range is formed by a line of volcanic cones. Rincón de la Vieja and Arenal Volcano exhibit volcanic activity. In 1968, Arenal Volcano began a period of spectacular activity, with emissions of lava, burning ash, and plumes of smoke. A small lake on the southern side of Arenal Volcano was later used to create a hydroelectric dam.
The Tilarán mountain range is made up of volcanic rocks where gold seams have been found in some areas such as Abangares and Miramar.
The Central Volcanic Mountain Range is formed by four volcanoes: Poás, Irazú, Barva, and Turrialba. Irazú Volcano exhibited significant volcanic activity between 1963 and 1965, during which time it displayed fumaroles, a hot spring area, and vents emitting magma and hot igneous rocks.
Poás Volcano has experienced volcanic activity at various times, including some ash eruptions. Acid rain is a phenomenon that is severely impacting the surrounding area, constantly damaging crops such as vegetables, strawberries, and many others.
Structurally, the Talamanca Mountain Range is an anticline, generally recognized by a sequence of rock layers that are progressively thicker towards the center of the cap, formed by marine sediments and volcanic rocks.
It begins in the Central Valley and runs in a northwest-southeast direction.
