Geological Formation
In geographical terms, the narrow land mass that is Central America, stretching from the Isthmus of Tehuantepec in Southern Mexico to the Isthmus of Panama, where it joins with the Colombian Pacific lowlands, is relatively young, forming for the most part in the Pliocene period, a mere 3 million years ago.
The region lies within the critical juncture where five important tectonic plates converge and crumple; the North American, Pacific, Coco’s, Nazca and Caribbean plates; its formation primarily the result of the ‘subduction’ or sliding, of the Coco’s plate under the Caribbean plate. The southernmost end of this isthmus, including the area that is now Costa Rica, sits along the western edge of the Caribbean plate where it is contested by the Coco’s plate.
The tectonic movement and subsequent volcanism that gave rise to this landmass began some 15-25 million years ago, in the Miocene period. At this time the Coco’s and Caribbean plates started moving towards one another, slowly colliding.
The Coco’s plate, shoving against the western edge of the Caribbean plate, nudging it eastwards, was heavier, containing a higher proportion of dense oceanic crust. As the two plates jostled together, wrestling for position, the heavier plate began to sink, nose-diving beneath the edge of the Caribbean plate. The ‘subducting’ plated descended beneath the Earth’s lithosphere, creating huge amounts of friction and heat and converting the heavy rock into less dense magma and gases. These then rose back upwards, collecting in intensely pressurized magma chambers and eventually erupting through the ocean floor; cooling to form an archipelago of submarine volcanoes bordering the Pacific in an arc extending from Guatemala to Panama.
Propelled by Coco’s dynamic burrowing, volcanic activity continued to thrust the ocean floor upwards, throwing more and more material down the slopes of the volcanoes until they emerged from the sea forming small islands. Deposits of sediment and rock, from both North and South America, slowly filled in the areas between them, eventually coalescing to form a continuous landmass approximately three million years ago.
Scientists describe this event as one of the most significant geological occurrences of the last 60 million years, the formation of the isthmus having had an enormous influence on the Earth’s climate and biological environment.
Where once the waters of the Pacific and Atlantic flowed and intermingled freely, this land bridge acted as a stopper, re-routing the marine currents, forcing Atlantic flows northwards to form new patterns of circulation, including what is today known as the Gulf Stream. The Gulf Stream sends warm Caribbean waters towards Europe, increasing the Continent’s temperature by as much as 10°C and thereby both directly and indirectly affecting global rainfall and other climatic, atmospheric and subsequently topographic patterns.
The development of a land bridge between the Continents of North and South America also played a vital role in facilitating biotic exchange between these two regions. This allowed both plant and animal species to migrate, mix and overlap, filling the area with a profusion of unique and exotic flora and fauna. The sustained volcanic activity that gave the region its extremes of elevation and relief was crucial in producing this impressively rich biodiversity; resulting in a vast array of micro climates draped over a characteristic spine of volcanoes, mountains and valleys stretching from Guatemala into Western Panama.
Costa Rica alone, despite representing less than 0.1% of the Earth’s surface contains some 112 volcanoes, 5 of which are still described as active; 3 large mountain ranges, the Cordillera de Guanacaste in the North, the Cordillera Volcanica Central and the Cordillera de Talamanca in the South - which contains the country’s highest peak, Mt Chirripo, at 3,819m - and is home to a huge 5% of global diversity.
The tectonic movement and subsequent volcanism that gave rise to this landmass began some 15-25 million years ago, in the Miocene period. At this time the Coco’s and Caribbean plates started moving towards one another, slowly colliding.
The Coco’s plate, shoving against the western edge of the Caribbean plate, nudging it eastwards, was heavier, containing a higher proportion of dense oceanic crust. As the two plates jostled together, wrestling for position, the heavier plate began to sink, nose-diving beneath the edge of the Caribbean plate. The ‘subducting’ plated descended beneath the Earth’s lithosphere, creating huge amounts of friction and heat and converting the heavy rock into less dense magma and gases. These then rose back upwards, collecting in intensely pressurized magma chambers and eventually erupting through the ocean floor; cooling to form an archipelago of submarine volcanoes bordering the Pacific in an arc extending from Guatemala to Panama.
Propelled by Coco’s dynamic burrowing, volcanic activity continued to thrust the ocean floor upwards, throwing more and more material down the slopes of the volcanoes until they emerged from the sea forming small islands. Deposits of sediment and rock, from both North and South America, slowly filled in the areas between them, eventually coalescing to form a continuous landmass approximately three million years ago.
Scientists describe this event as one of the most significant geological occurrences of the last 60 million years, the formation of the isthmus having had an enormous influence on the Earth’s climate and biological environment.
Where once the waters of the Pacific and Atlantic flowed and intermingled freely, this land bridge acted as a stopper, re-routing the marine currents, forcing Atlantic flows northwards to form new patterns of circulation, including what is today known as the Gulf Stream. The Gulf Stream sends warm Caribbean waters towards Europe, increasing the Continent’s temperature by as much as 10°C and thereby both directly and indirectly affecting global rainfall and other climatic, atmospheric and subsequently topographic patterns.
The development of a land bridge between the Continents of North and South America also played a vital role in facilitating biotic exchange between these two regions. This allowed both plant and animal species to migrate, mix and overlap, filling the area with a profusion of unique and exotic flora and fauna. The sustained volcanic activity that gave the region its extremes of elevation and relief was crucial in producing this impressively rich biodiversity; resulting in a vast array of micro climates draped over a characteristic spine of volcanoes, mountains and valleys stretching from Guatemala into Western Panama.
Costa Rica alone, despite representing less than 0.1% of the Earth’s surface contains some 112 volcanoes, 5 of which are still described as active; 3 large mountain ranges, the Cordillera de Guanacaste in the North, the Cordillera Volcanica Central and the Cordillera de Talamanca in the South - which contains the country’s highest peak, Mt Chirripo, at 3,819m - and is home to a huge 5% of global diversity.
