#ahaggar

[vestaignis]

Ахаггар в цвету. Фотограф Fortuna Fabrizio. Италия (Rome). Ahaggar in bloom. Photograph by Fortuna Fabrizio. Italy (Rome).

Источник: /35photo.pro/photo_12087529/.

[cesarojedac]

[mydearalgeria]

Algeria. Portrait of a Bel Tamasheq/Tuareg woman in traditional attire and jewels, Ahaggar region  - 1920/1939.

[weltundkosmos]

Camellero sobre su dromedario, en Ahaggar, Argelia (2006).

[earthstory]

Hoggar Mountains, Algeria

This image shows an ancient volcano located in southern Algeria. After some searching, I believe the correct name for this object is the Lharen phonolitic plug.

This photo was taken in an area of southern Algeria known as the Hoggar Mountains which makes up the Ahaggar National Park (Hoggar and Ahaggar seem to be interchangeable in the translations).

The Hoggar Mountains sit in the heart of the Saharan desert close to the southern tip of Algeria, close to the Tropic of Cancer. They sit on top of a broad plateau and are composed of volcanic rocks erupted over the last 40 million years. The most active portion of the volcanism took place between 12 and 20 million years ago and the rocks in this image date from that period.

This outcrop is a volcanic plug, the remnants of the inside of a volcano. This rock was formed by lava that migrated upwards inside a volcanic system but was stranded when the supply from below was cut off and the volcano died.

The rocks show columnar jointing; that’s the pattern of near vertical lines and cracks you see. Columnar jointing always forms lines in the direction cooling is happening; this rock cooled from above, suggesting that it was originally surrounded by a larger volcanic mass that shielded the sides from cooling.

Most of the outer volcano has been eroded away, but the plug in the volcano likely cooled slowly, generating a crystalline rock which is strong and resistant to erosion. The debris pile around it is some remnants of the erosion of the plug and the mountain around it. The rock itself is a phonolite, a common type of magma found in crustal igneous settings.

The cause of the volcanism in this area is enigmatic. The volcanic rocks are coming through the thick crust of northern Africa but have chemical signatures suggesting they were derived from the mantle. They could have been formed due to a small hotspot underneath this portion of Africa, or they could represent a product of the collision between Europe and Asia far to the north, which could break the crust throughout the continent and cause enough movement within the mantle to cause generation of the magmas that eventually formed this plug.

-JBB

Image credit: Patrick Gruban http://www.flickr.com/photos/gruban/137349085/

A data compilation source thanks to Dr. Anderson’s page: http://www.mantleplumes.org/Hoggar.html

World Geography entry: http://world-geography.org/mountain/12-ahaggar-mountains.html

http://www.volcanolive.com/tahalra.html

[mydearalgeria]

Algeria. Basketwork by a Tuareg girl from the Ahaggar region, Tamanrasset - 1975.

Henri Bancaud. 

[mydearalgeria]

Magnificent portrait of two children from the Ahaggar in the wilaya of Tamanrasset, southern Algeria - 1975.

Henri Bancaud.

[mydearalgeria]

Algeria. Young Tuareg girl from the Ahaggar - early 70s

Kazuyoshi Nomachi.