Some geological pictures from Kenya

Menengai Crater, Southwest Kenya. A major volcanic crater in the East African Rift. This and other volcanoes are characteristic of the East African Rift. Liquid magma rose along the deep seated faults associated with the rift. Rifts form where the forces of plate tectonic cause large blocks of the upper mantle and earth crust to move apart, allowing magma to rise from the upper mantle. Photo taken standing on the west wall of the crater and looking toward the hills in background that form the north and east walls of the crater. The lavas of the crater are trachytes, whereas pumice, obsidian, and scoria form the rim. The crater is 8-10 km in diameter and 485 m deep.



Overview of Menengai Crater, Southwest Kenya. Signpost indicates 12,360 miles to New York and 13,687 miles to Evanston, Indiana. It is 138 miles west of Mt. Kenya and 148 miles northwest of Nairobi, the capital of Kenya.



Hot springs with mound of silicious sinter deposited from the springs, Lake Bogoria, Southwest Kenya. Lake Bogoria is one of a chain of lakes situated in the East African Rift. Hot springs also are characteristic of the East Africa Rift. Ground waters are heated by rising magmas and hot rocks, and the lighter hot water and steam rises to the surface by the force gravity. The entry of hot spring water into the lake waters warms those waters. Huge flocks of flamingos feed on the abundant algae that thrive in the warm waters of Lake Bogoria and other Great Rift Valley lakes. Lake Bogoria is characteristic of a chain of salty lakes present in the Great Rift Valley.



Fisher's Tower, Hells Gate National Park, near Lake Naivasha , Southwest Kenya. The tower is a volcanic neck. Magma filled and solidified in the neck of the volcanoe, and subsequently the pyroclastic rocks in its vicinity were eroded away to leave the volcanic neck as an erosional pinnacle. About 140 miles northwest of Nairobi.



Columnar jointing in pyroclastic rocks at Hells Gate National Park, near Lake Naivasha, Southwest Kenya. Columnar jointing consists of parallel prismatic columns that have polygonal cross sections. This type of jointing forms in thin volcanic rock bodies as a result of contraction during cooling of the extrusive magma.



Diatomaceous lake beds at the edge of salty Lake Elmenteita. Diatomaceous earth is a light colored soft friable siliceous sedimentary rock. It consist of opal or quartz that formed the siliceous walls of diatoms, a microscopic single-celled plant. The rocks are mined for the diatomaceous earth that has high surface area, high absorptive capacity, and chemical stabilty, properties that find use as filters, and as extenders in paint, rubber, and plastics. About 130 miles northwest of Nairobi.



Ol Karia Geothermal Field, near Lake Naivasha, about 80 miles northwest of Nairobi. Electrical energy is generated from the steam harnessed into pipes from underground water courses. The natural water has been heated by the presence of magma and heated rocks at depth. The Tertiary volcanic rocks are rhyolites, alkali rhyolites, and pyroclastics.

ZDROJ:http://web.umr.edu/~rhagni/Kenya.html