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Imaggeo on Mondays: A Colombian myth with geologic origins

Imaggeo on Mondays: A Colombian myth with geologic origins

This photograph shows El salto del Tequendama, a natural waterfall of Colombia, located in the Department of Cundinamarca at an altitude of 2400 metres above sea level and approximately 30 kilometres southwest of the country’s capital, Bogotá.

The Salto del Tequendama is a space of transit and connectivity between the warm lands of the Magdalena river basin and the cold lands of the Sumapaz paramo, a Neotropical alpine tundra located at 4,000 metres above sea level.

Dutch-Colombian geologist Thomas Van der Hammen concluded that approximately 60,000 years ago the entire savannah of Bogota (populated today by 9 million people) was covered by a large lake, known as the Humboldt Lake, and the associated wetland plants instead of the paramo vegetation seen today.

Over time, the climate became warmer and the bottom of the Humboldt Lake began to rise. 30,000 years ago, the lake’s waters were channelled through the Bogota River and led to the Salto del Tequendama, a real climate event that we Colombians received through the myth of Bochica, a legendary hero to the Colombian indigenous group the Muisca. Here is the summarised myth of Bochica and the Tequendama jump:

“… As the Muiscas had lost respect for the gods, they offended Chibchacum, who had previously been the most beloved of their gods. He decided to punish them by flooding the savanna, for which he gave birth to the Sopo and Tivito rivers, which joined their rivers to the Funza (former name of the Bogotá River). The flood ended with many crops and human lives, until the people clamored with fasting and sacrifices to Bochica to free them from that calamity. The sage Bochica appeared on the rainbow and with his golden scepter, hit the rocks allowing the water to form a gigantic waterfall. So Bochica created the Tequendama jump.”

The large lake was partially dried and separated into smaller wetlands, where Andean plants, deer, foxes, weasels and more than 100 bird species made their home.

The waterfall, famous for its size, surrounding vegetation and vapourous waters, has been widely studied since 1668, when the Bishop of Panamá, Lucas Fernández de Piedrahíta made the first written record of its mythical origin story.

During the 18th and 19th centuries in particular, the Salto was one of the most famous natural attractions both locally and worldwide, due to the waterfall’s 157-metre drop onto a circular rocky abyss in a wooded region of permanent haze.

In the 19th century, large estates, also known as haciendas, were built on the region’s wetlands, and the natural environment was converted into places for fishing, hunting and logging. Through drainage channels, communities dried up the land to establish livestock and agricultural systems. In the last century, as the city of Bogota grew in population and size, the wetlands were filled to build neighborhoods, streets and avenues.

Like many Bogotanos, on a family weekend trip to relieve the stress generated by the chaos of the city and in search of clean air, I took this picture. The Salto was and always has been a fundamental part of the Bogota family mythology.

By Maria Cristina Arenas Bautista, National University of Colombia, Department of Civil Engineering and Agricultural (Bogotá)

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: The most powerful waterfall in Europe

On the menu this Monday is the opportunity to indulge in some incredible Icelandic geology. Take a look at a tremendous waterfall and the beautiful basalt it cuts through…

Iceland is famous for its striking landscapes, from fiery volcanoes and fields of basalt to violent geysers and pools of the most fantastic blue. One of the country’s many geological gems is Dettifoss waterfall – a 100-metre-high mass of white, tumbling water within Vatnajökull National Park.

With about 200 cubic metres of water falling each second, Dettifoss is widely reported to be the most powerful waterfall in Europe. It certainly looks the part.

Dettifoss waterfall, Iceland (Credit: Neil Davies, via imaggeo.egu.eu)

Dettifoss waterfall, Iceland (Credit: Neil Davies, via imaggeo.egu.eu)

Dettifoss is fed by melt from the Vatna Glacier (Vatnajökull), and the spring spike in meltwater means the fall’s flow can reach some 1500 cubic metres per second. By putting your hand to the rocks beside the fall you can feel the thundering torrents as the basalt vibrates beneath your fingertips.

The Jökulsá river snakes through the park’s volcanic canyons, which are constantly being cut by the erosive force of the fall. Dettifoss isn’t the only great feature in this photo though: the canyon walls are layered with lava flows that – even at a glance – reveal when they were deposited. The relatively smooth deposit at the base of the wall and the thinner skin of smooth basalt in the middle are the product of interglacial eruptions. The two rough, blocky-looking layers are columnar basalt deposits – a feature that forms when lava meets ice and cools so rapidly that it fractures into long, hexagonal columns.

Dettifoss up close. (Credit: Roger McLassus)

Dettifoss up close. (Credit: Roger McLassus)

For many geoscientists, Iceland is the top spot on the geological destination list. If you went to Iceland, where would you go? Been before? Tell the tale. We’d love to hear from you.

By Sara Mynott, EGU Communications Officer

Reference:

Bamlett, M., and Potter, J. F.: Icelandic geology: an explanatory excursion guide based on a 1986 Field Meeting. Proceedings of the Geologists’ Association 99.3, 221-248, 1988.

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

Imaggeo on Mondays: Winter waterfalls reveal their secrets

Cyril Mayaud is kicking of this week’s Imaggeo on Mondays with an insight into what waterfalls in winter can tell us about their local hydrology… 

The picture below shows the lower Peričnik waterfall during winter season. This cascade system is composed of two successive waterfalls that stretch some 16 metres (upper fall) and 52 metres (lower fall) high and is one of the most beautiful natural sights in the Triglav National Park. The cliff is located at the western rim of a U shaped valley and is composed of a very permeable conglomerate rock, which is made up of glacier material that accumulated at the rims of the valley back when the glacier retreated.

Peričnik waterfall from behind the scenes. (Credit: Cyril Mayaud

Peričnik waterfall from behind the scenes. (Credit: Cyril Mayaud

The high permeability of the rock provides an important path for water transfer, letting it infiltrate between the level of the upper and the lower fall. This transfer is particularly visible if you walk in the passage under the fall, where the infiltrated water falls at an intensity comparable to a strong shower. Winter is also a fascinating time to visit the falls and see how the water flows from the upper level to the lower level. The low temperatures freeze the dripping water, creating a picturesque landscape with beautiful ice stalactites and draperies.

Peričnik waterfall, an amazing sight in Slovenia’s Triglav National Park. (Credit: Cyril Mayaud, distributed by imaggeo.egu.eu)

Peričnik waterfall, an amazing sight in Slovenia’s Triglav National Park. (Credit: Cyril Mayaud, distributed by imaggeo.egu.eu)

As hydrogeologist, I see two key scientific points of interest in this picture: the first relates to the water transfer between the two levels, which is delayed during winter (due to the low temperatures) as it shows a spatial snapshot of the infiltration processes through the outcrop. The second underlines the importance of accurately quantifying all the different hydrological processes in a given catchment in order to better understand its hydrological behaviour. As an example, the storage of water as snow is really important for mountainous catchments (like the catchment of the Fraser River in British Columbia) and plays a prominent role in retaining water during the cold season and releasing it during spring/summer.

The waterfall in summer, a wonderful view. (Credit: Cyril Mayaud)

The waterfall in summer, a wonderful view. (Credit: Cyril Mayaud)

A parallel could be also made with the hydrological behaviour of karst aquifers, which depend on a variety of processes, each with different time scales. Because these aquifers contain fractures with a huge size range (from cracks less than 1 mm wide to conduits bigger than 10 metres), these aquifers allow water to infiltrate in two very different ways, and are said to have a double infiltration capacity: rapid and localised infiltration through sinkholes and ponors, and slow, diffuse infiltration of rainwater in the unsaturated zone. The origin and path of the water can normally be differentiated during chemical sampling in the spring.

By Cyril Mayaud, University of Graz  Austria

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.