Volcanoes on Ascension Island

August 2015

In terms of geology, Ascension Island is relatively young and was created by intense volcanic activity generated from the Mid-Atlantic ridge, the same chain of underwater volcanoes that formed Iceland, the Azores and other small islands throughout the Atlantic ocean. Ascension Island now has 44 volcanic cones all dormant since at least six centuries, which are a paradise for geologists and landscape photographers.

Ascension volcanoes Ascension volcano
Ascension Island has a total area of only 88 square kilometers, but hosting well 44 volcanic cones that have gradually ceased their activity during past epochs (the most recent seems to have erupted about 6 centuries ago). Ascension Island is therefore a paradise for geologists, as the erupted rocks are generally exposed and not hidden under a real soil or vegetation.

 

Volcanic crater
On Ascension Island there are many trails of varying difficulty, crossing immense solidified lava fields and offering exceptional views across the various volcanic cones.

 

Sister Peak Ascension
Ancient lava flow Dormant volcano
Photos of Ascension Island volcanoes: the beautiful complex of volcanic cones called Sister Peak, which was active until about 600 years ago. The highest crater reaches an altitude of 450 meters and the area is easily accessible from the road connecting Georgetown to English Bay. Just be sure to bring robust trekking shoes, plenty of water, hat, lot of sunscreen and keep in mind that the heat could be intense, because the ground is very dark and there is no vegetation.

 

A sign at the trailhead for Sister Peak warns that the area is sometimes used by the military as a shooting range, therefore it is essential to not touch any ammunition that may be present.

 

Volcano on Ascension Ascension Island volcano
Volcanic landscape Ancient eruption
The beautiful volcanic landscape of Ascension Island at the foot of Sister Peak, the recentmost craters of the island.

 

The vegetation in the vicinity of the youngest volcanic cones began to appear only in recent decades and can't be seen in historical photos of Ascension.

 

Volcanic cones
Volcanic cone Volcano
Volcanoes Volcanic crater
Although there is a kind of path, climbing a volcanic cone proves rather strenous, as the soil composed predominantly of pozzolan, pumice and other highly porous rocks, is very soft, and is almost like climbing sand dunes. The beauty of the landscape and the colors, however, reward for all the efforts.

 

Volcanic soil
Details on volcanic soil around the craters in Sister Peak. In the right picture you can notice tiny pine cones produced by a conifer that is slowly colonizing this arid and ungrateful environment.

 

More photos of Ascension and extinct volcanoes, where lava rocks show different colors depending on chemical composition.

 

Rainbow
A rainbow among the volcanoes of Ascension.

 

Cross Hill Ascension Island
Roads on the volcano
Cross Hill is a beautiful volcanic cone just behind Georgetown and a narrow road make possible to climb up to a nice lookout.

 

The Green Mountain (the mountain on the right of the photo) is the largest and oldest extint volcano of Ascension Island. Because of currents and temperature patterns, the rainfall on Green Mountain is much higher than the rest of the island, so the vegetation is much more abundant and lush.

 

Donkeys Donkey
The wild donkeys graze freely among Ascension's volcanoes.

 

Wherever you are on the island, the scene is always dominated by some dormant volcano.

 

South Gannet Hill
South Gannet Hill is a volcanic cone near the US military base near Ascension airfield. At the top there is a strange installation and a sign warns that it's not possible to continue driving up without a permit.

 

Ascension Island endemic flora Euphorbia origanoides
Ascension Spurce Euphorbia on Ascension

But the South Gannet hill is particularly known and important, as it hosts one of the few plant species endemic to Ascension still in life: the Euphorbia origanoides. This plant is among one of the rarest in the world and is considered to be in great danger of extinction because, except for some collection in botanical gardens, the only place in the world where you can find it, is exclusively among this volcano on Ascension Island.

In these pictures of Euphorbia origanoides, we can observe the plant as it appears in August, during flowering time. The Euphorbia origanoides is also known locally as "Ascension Spurge" and is classified by the IUCN (the world authority which classifies species according to the number of individuals present in nature) as CR (critically endangered).

 

Orange lichen
Mosses and lichens that are trying to colonize a barren lava field.

 

Sooty terns nesting

Near South Gannet hill there is also an important area for sooty terns: during favourable years, in summertime, thousands of couples come here to nest.

 

Breadcrust bomb
White lava Ascension Island is a paradise for geologists, offering the chances to observe a multitude of volcanic rocks. In the top left picture, odd sheets of lava. In the photo above, a volcanic bomb, often referred as "breadcrust bomb" due to its shape and pattern of the surface. In the bottom-left picture, a white lava rock rich in magnesium.

 

Centipede
A poisonous centipede wandering on a lava field.

 

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