36 
AFRICA AND ITS EXPLORATION. 
again. At Niagara the formation is limestone, and it 
is calculated that the water has taken some millions of 
years to excavate the channel. Here the soil is hard 
granite rock, and it is a pretty problem for geologists 
THE HUNDRED FALLS. 
to decide, by analogy, the age of this part of the African 
Continent. 
During our explorations we counted, and mapped 
down, and named, nearly a hundred distinct cascades, 
and this fact gave me the idea of calling the falls of the 
Orange River “ The Hundred Falls.” If the reader will 
