The Barrier is an active shield volcano located in the north of

Kenya ) , national_anthem = " Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi ...

. It is last known to have erupted in 1921.

Description

The Barrier was given its name because it forms a barrier about long across the

Kenyan Rift Valley The Great Rift Valley is part of an intra-continental ridge system that runs through Kenya from north to south. It is part of the Gregory Rift, the eastern branch of the East African Rift, which starts in Tanzania to the south and continues ...

. It has a width of and separates Lake Turkana to the north and the Suguta Valley and the small Lake Logipi to the south. The volcanic complex consists of four distinct volcanoes. From west to east these are Kalolenyang, Kakorinya, Likaiu West and Likaiu East. The foundation rocks are mainly

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

. About 90% of the volume is

trachyte Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava enriched with silica and al ...

. Kakorinya is the youngest of the group and forms the center of the complex, with a well-preserved circular crater that has not been breached. The wide summit caldera of Kakorinya was formed about 92,000 years ago. Much of the floor of the caldera is filled with trachytic and

phonolitic Phonolite is an uncommon extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a variation of the igneous ...

lava domes and flows that recently erupted within the caldera and along its ring fracture. There are

scoria Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock that was ejected from a volcano as a molten blob and cooled in the air to form discrete grains or clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) '' ...

cones and lava flows from the early

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

on the north and south flanks of the volcano complex. In the 19th and 20th centuries there have been explosive eruptions and lava flows from Teleki on the northern side and from Andrew's cone on the south side of Kakorinya. The last known eruption was in 1921.

References

Sources

* * Polygenetic shield volcanoes Volcanoes of Kenya Active volcanoes {{Kenya-geo-stub

Description

See also

References

Sources