Tuesday, 9 September 2014

Day 3 - Welcome to Sleeping Warrior!

Today, it is a visit to Sleeping Warrior, aka Split Crater.

According to Google, it was a 50 minute drive to the south of Menengai, very close to Lake Elementaita. Google didn't take in to consideration the awful road conditions, the vibrations of which broke the fan that cooled the engine!

Sleeping Warrior is the Masai name for the volcano. It looks a little like someone sleeping on their back.

Sleeping Warrior

Masai legends say that boys and young men were taken to the volcano to be circumcised. But one day something went wrong and the boy bled to death. Masai elders today insist that their warrior is not dead but in a deep long sleep in the volcano. 

The thought behind the visit to the volcano was to make observations on the interaction of faulting with volcanoes of the EAR. The split across the middle of the volcano is a fault that measures approximately 1km in length on a north-south trend, with vertical displacement dropping the left flank in the image above (Image taken looking south). Due to weathering and the lithologies, structural observations were not possible. 

For the climb, we were accompanied by a guide and a scout because of dangerous animals. We were treated to zebra and gazelles.

1096 m.a.s.l. at the neck of the volcano on the northern flank, layers of silt and sand were found to contain gastropods and bivalves. The fossils were well articulated, measured 0.5 - 1cm in length.
There was also evidence of cross bedding in medium grained sandstones, overlain by silts and further overlain by well rounded conglomerates, above which there were lavas. The lavas were quite dark in colour on a fresh surface and fractured with in fill of a paler lithology interpreted to possibly be trachyte as the grains were too small for a clear identification. 

Gastropods in sediments 

Cross bedding in sediments

The top of the volcano was 2036 m.a.s.l. on the foot wall, eastern flank. The views were amazing!

360 panoramic from the top of the volcano

With our guide Phillip and our scout Jeoffrey with Lake Elementaita in the background (Image taken looking north). 

The southern edge of the crater from inside. The crater floor is now covered in vegetation and there is no fault trace, suggesting there has been no movement along the fault since before the cooling of the lava lake. 

Walking across the crater, we did have a lion scare. It was a pale coloured cow and not down to my eyes, but my field assists!

Lake Navaisha, Lake Elementaita and Lake Nakuru were linked as one lake years before the rifting began. The different deposits support different environments with the cross bedding suggesting a period of time where there was a current or flow in the lakes, the silts support a time of very clam and possibly even a deeper environment and  the conglomerates may be from flash flooding. 

Rifting followed this with plume heads causing doming of the crust both locally and regionally. With the doming caused by rising magma. partial melting of the lower crust would rise to the surface forming volcanoes. The volcano sits on the elevated and thinned rift floor and is surrounded by several other volcanoes and cinder cones. 

Lala Salama from Kenya!

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