200 
appendix. NO. IV. 
probably in connection with the rock-salt of the neighbour- 
hood, which, from the number of brine springs discovered 
feeding the river, must necessarily exist. 
Variety of the same description of rock. 
Jasper and Quartz. — Shewing itself above the surface of a plain, 
from which D’Urban’s group bore S. 40 E. distant 33 miles. 
It is a remarkable fact, that not a pebble or a stone was pick- 
ed up during the progress of the expedition, on any one of the 
plains ; and that after it again left Mount Harris for the Castle- 
reagh, the only rock-formation discovered was a small Free- 
stone tract near the Darling river. There was not a pebble of 
any kind either in the bed of the Castlereagh, or in the creeks fall- 
ing into it. 
