154 CAPTAIN TUCKEY’S NARRATIVE. 
The margin of the river and the rocks in it are of mi- 
caceous slate; next to which small hills of loose round 
pebbles of quartz; then more elevated hills of ferruginous 
clay with masses of quartz; next hills of yellow clay with 
masses of sienite ; and lastly, steep hills with rocky sides, 
(sienite), but with long levels at the summit, covered with a 
fertile vegetable soil, and on which most of the banzas are 
situated. The hills of quartz pebbles have every appearance 
of once having been the bed of the river, the pebbles having 
evidently been rounded, and the hills received their forms, 
by the long and violent action of water. If we assume, what 
seems highly probable, that the present obstruction at Yel- 
lala was once a real cataract of equal elevation with the op- 
posite shores, this surmise of the river having formed these 
hills of pebbles will acquire a certainty ; for in that case, the 
water kept up by the cross ridge or cataract would have 
covered these hills. A great quantity of quartz sand is 
thrown up on the sides of the river among the rocks. 
At night the hills appear to be ina continued blaze of fire, 
from the hunters in the day setting fire to the long dry grass 
to drive out the animals. ‘The fire running to windward, 
as is always the case, the hunters keep to leeward of the spot 
fired, and the game, it would appear, being also aware of 
the direction which the fire will take, endeavour to avoid it, 
by also running to leeward, and consequently throw them- 
