768 ROLLIN T. CHAMBERLIN 
in by several scarcely less massive cones which would seem to 
provide ample sources for the borate in the basin. 
Beyond the station of Ollagiie the train, turning more to the 
east, leaves the volcanic Cordillera and makes its way over the 
Great Central Plateau to Uyuni and Oruro. This region is a great 
detritus-strewn plain with low ridges and ranges trending generally 
north and south. Salt marshes and old lake beds continue, but 
as the volcanoes are left behind, the deposits of borax rapidly 
disappear. There are no known borate deposits associated with 
the non-volcanic Eastern Cordillera. 
