270 Transactions of the Boyal Society of Soutli Africa. 
sketch plan and section (see figure) along the last 3^ miles of the valley 
yjQTQ made by pacing and anaeroid readings, but they illustrate its chief 
features sufficiently closely for our purpose. The drop from the highest 
terrace (where Henkries water is situated) to the river is about 400 feet, or 
