Volcanoes Create Blue Rivers
Rincon de la Vieja National Park - the volcano crater from Blue River Resort & Hot Springs
Looking into the crater of Rincon de la Vieja volcano
Part III – Posted June 2017
Costa Rica’s rivers are byproducts of her volcanoes which form the backbone of the Country. They were created long ago by geological activity on the earth’s crust. Though we celebrate the blue rivers, there are many differently colored rivers in Costa Rica.
Coloring a River
Minerals gathered from the volcano are transported in the water and create the unusual colors in many of the rivers; perhaps not in the manner you would expect. These are not just ordinary rivers with a mild discoloration. Some are as blue as the sky, others are sunset yellow and there are the green ones; all are influenced by the volcanoes. After a hard rain, they turn a shade of brown temporarily but quickly return to their original colors.
How Volcanoes Create Rivers
We tend to remember the fiery nature of volcanoes but seldom associate them with the rivers they produce. The lofty volcanoes redirect the wet humid winds of the Caribbean up its slopes where they cool and release moisture as rainfall. This provides an almost continuous source of water to irrigate the lush tropical rainforest. Some rainwater is captured by the volcano’s exposed crater; it filters down its shaft, collecting minerals along the way. This water can later bubble up to the surface infused with minerals, as hot springs. The ‘aluminum-silicate’ that bubbles up in tributaries becomes sediment covering a riverbed, to form blue rivers. The remainder of the rainwater collects on the surface forming the rivers.
There are 14 major river systems feeding eighty major rivers and numerous smaller tributaries winding down the slopes. Thirty-five of the larger rivers flow into the Caribbean Sea on the Atlantic Ocean side and another 43 rivers flow into the Pacific Ocean. The San Juan River flows along the border with Nicaragua into Lake Nicaragua.
The Volcanoes of Costa Rica
Arenal Volcano Eruption
Irazu Volcano Costa Rica
There are over 200 volcanic formations across the Country. One hundred of them show no signs of activity (not in the last century anyway). However, another five of them remain ‘active’. Occasionally, one will rumble, thunder, and display a spectacular pyrotechnic show. It is quite beautiful against the backdrop of a night-sky studded with stars.
Costa Rica’s volcanic features were created by two tectonic plates (i.e. plates forming the Earth’s crust) coming together from opposite directions. They impacted beneath the Isthmus of Panama connecting mainland USA to South America. The Caribbean Plate in the east crushed into the Cocos Plate of the Pacific traveling westerly; the Cocos Plate became the subduction or lower plate. The process forced the creation of Central America and its many volcanoes. It all started in a process beginning millions of years ago and continues. Costa Rica gets marginally higher every year.
The land rising on the Isthmus, from the seabed, formed the link between the two continents. The molten activity taking place beneath the plates seeped to the surface and developed the volcanoes. The series of volcanoes running through Guatemala, El Salvador, Nicaragua, and Costa Rica is called the Central American Volcanic Arc; a sub-section of the Pacific Ring of Fire on the Equator.
For more in our blog on this topic, read Costa Rica Volcanoes
Rincon de la Vieja Volcano- The Old Woman's Corner
Geologists find a literal hotbed of activity at Costa Rica's Turrialba Volcano
Blue Rivers of Costa Rica - Blog Contents
Intro - Costa Rica's Blue Rivers
A special allure
Part I – What a Blue River is
The scientific explanation for blue rivers.
Part II - Rio Celeste vs. Rio Azul vs. Rio Penjamo
Fantastic Eco-tourism and adventure in and along these blue rivers