Triple Junction, East Africa
In the Afar region of Ethiopia, a nearly barren rockscape marks the location of the meeting place of three separate pieces of Earth’s
crust known to geologists as the Afar Triple Junction. Here, the spreading ridges that form the Red Sea and the Gulf of Aden emerge
on land and meet the East African Rift. The central meeting place for these pieces is around Lake Abbe, just to the south of the area
shown in this 2005 Terra image.
The three pieces are each pulling away from that central point, though not all at the same speed. The separation creates enormous
stress on the rock, producing cracks, faults, volcanoes, fumaroles (gas vents), escarpments, and hot springs in the region along the
border of Ethiopia, Eritrea, and Djibouti. One of Earth’s few lava lakes, Erta Ale, is found in this area. In the image, the gray-brown,
ancient, basalt rock of the region is crisscrossed by cracks both small and large, many of which are filled with salt and sand. The
tinge of red indicates some hardy vegetation eking out a living in the harsh terrain. The large riverlike feature running horizontally
across the scene is a geologic feature called a graben, a gulley created not by the erosion of a river but by the sinking of the ground
where earth on either side pulls apart.
The Afar region is well known as one of the cradles of hominids. The region contains the Middle Awash, the site of many fossil
hominid discoveries; Gona, the site of the world’s oldest stone tools; and Hadar, the site of a fossilized specimen of Australopithecus
afarensis known as Lucy. NASA