1872.] GEOLOGICAL NOTES. 217 



The black basaltic mountains on the east of the Bamang- 

 wato, formerly called the Bakaa, furnish further evidence of 

 the igneous eruptions being sub-aerial, for the basalt itself is 

 columnar at many points, and at other points the tops of tin • 

 huge crystals appear in groups, and the apices not flattened, 

 as would have been the case had they been developed under 

 the enormous pressure of an ocean. A few miles on their 

 south a hot salt fountain boils forth and tells of interior 

 heat. Another, far to the south-east, and of fresh water, 

 tells the same tale. 



Subsequently to the period of gigantic volcanic action, 

 the outflow of fresh lime-water from the bowels of the earth 

 seems to have been extremely large. The land now so dry 

 that one might wander in various directions (especially west- 

 wards, to the Kalahari), and perish for lack of the precious 

 fluid as certainly as if he were in the interior of Australia, 

 was once bisected in all directions by flowing streams and 

 great rivers, whose course was mainly to the south. These 

 river beds are still called by the natives " melapo " in the 

 south, but in the north " wadys," both words meaning the 

 same thing, " river beds in which no water ever now flows." 

 To feed these a vast number of gushing fountains poured 

 forth for ages a perennial supply. When the eye of the 

 fountain is seen it is an oval or oblong orifice, the lower 

 portion distinctly water worn, and there, by diminished size, 

 showing that as ages elapsed the smaller water supply had 

 a manifestly lesser erosive power. In the sides of the 

 mountain Amhan, already mentioned, good specimens of 

 these water-worn orifices still exist, and are inhabited by 

 swarms of bees, whose hives are quite protected from robbers 

 by the hardness of the basaltic rocks. The points on which 

 the streams of water fell are hollowed by its action, and the 

 space around which the water splashed is covered by cal- 

 careous tufa, deposited there by the evaporation of the sun. 



Another good specimen of the ancient fountains is in a 



