Home Top

Footprint of a billion-year-old volcano revealed: Satellite images show the bizarre perfect circles left by ancient lava flows in South Africa

Image shows concentric rings of volcanic rock in Pilanesberg National Park forming a near perfect circle
Rocks are believed to have been created by an ancient volcano which collapsed in on itself billion years ago
This squeezed magma out from the ground, which cooled to form stunning, lasting structures called dikes

By Ellie Zolfagharifard For Dailymail.com

Published: 14:31 EST, 3 August 2015 | Updated: 02:16 EST, 4 August 2015

View
comments

The footprint of a billion-year-old collapsed volcano has been revealed in a satellite Nasa image of South Africa’s Pilanesberg National Park.

Pilanesberg has the world’s largest alkaline ring dike complexes - a rare circular feature that emerged from the subterranean plumbing of an ancient volcano.

Seen from space, the concentric rings of hills and valleys make a near perfect circle, with different rings made up of different types of volcanic rock.

The footprint of a billion-year-old collapsed volcano has been revealed in a stunning Nasa image of South Africa’s Pilanesberg National Park. Pilanesberg has the world’s largest alkaline ring dike complexes - a rare circular feature that emerged from the subterranean plumbing of an ancient volcano. Seen from space, the concentric rings of hills and valleys make a near perfect circle

HOW WERE THE RINGS CREATED?

A billion years ago, magma pooled up near the surface of the region in a large hot spot that bulged with immense pressure, creating a volcano.

After several eruptions, the centre of an ancient volcano in the collapsed on itself, squeezing magma out from the ground.

The magma cooled in the cracks as bands of volcanic rock, mainly rock named syenites and foyaites, which are called dikes.

The rate of cooling and the makeup of the magma affected the type of rock that formed in each dike.

These rock types are especially resistant to erosion and weathering. They were left behind as stunning hills and ridges that can be seen in the region today.

The entire structure sits about 300 to 1,600ft (100 to 500 meters) above the surrounding landscape. The highest point - Matlhorwe Peak - rises 5,118ft (1,560 metres) above sea level.

Several streams run through the valleys and faults, though most only flow during the wet season between October and April.

‘When this image was taken in June, the streams had run dry, revealing the incredible billion-year-old structure in stunning detail,’ sayd Nasa.

‘Several phases of geologic activity created the landscape over hundreds of millions of years.’

The process began about 1.3 billion years ago, when Earth’s very first primitive organisms, like algae, were the only life forms on Earth and huge volcanic eruptions were common.

During this period, magma pooled up near the surface in a large hot spot that bulged with immense pressure.

The pressure helped push up a volcanic structure that was several thousand metres tall. Over time, tubes of magma radiated outward from the main magma chamber beneath the volcano.

Eventually, this created huge cracks in the Earth’s surface around the volcano at regular intervals.

In cross section, the magma tubes would have looked something like the branches of a tree extending from a common trunk.

From above, the radial cracks gave the surface the appearance of a broken window.

The rate of cooling and the makeup of the magma affected the type of rock that formed in each dike. For instance, white foyaite has particularly coarse grains and is formed when lava cools slowly. Red syenite forms when magma contains plenty of water. In the detail image, outcrops of white and green foyaite and of red syenite make up the ridges in the southwestern part of the park

The entire structure sits about 300 to 1,600ft (100 to 500 meters) above the surrounding landscape. The highest point - Matlhorwe Peak - rises 5,118ft (1,560 metres) above sea level. The Pilanesberg Game Reserve is in North West Province in South Africa, west of Pretoria

Scientists believe after several violent eruptions sent lava bursting from the volcano, the centre collapsed on itself, squeezing more magma out from the network of cracks.

As volcanic activity slowed, the magma cooled in the cracks as bands of volcanic rock, mainly rock named syenites and foyaites. Geologists call these structures dikes.

The rate of cooling and the makeup of the magma affected the type of rock that formed in each dike.

For instance, white foyaite has particularly coarse grains and is formed when lava cools slowly.

Red syenite forms when magma contains plenty of water. In the detail image, outcrops of white and green foyaite and of red syenite make up the ridges in the southwestern part of the park.

These rock types are especially resistant to erosion and weathering. They were left behind as stunning hills and ridges that can be seen in the region today.

The process to create this structure began about 1.3 billion years ago, when Earth’s very first primitive organisms, like algae, were the only life forms on Earth and huge volcanic eruptions were common

While big game animals such as lions, leopards, elephants, rhinos, and water buffaloes draw most visitors to Pilanesberg National Park, the land these animals live on is just as compelling

Angry elephant in Pilanesberg National Park scares tourists!