66 
TRAVELS IN 
perpendicuTarly from time to time along that coaft, are indica- 
tions that fufficiently warrant this conclufion. 
It may alfo be obferved, with regard to the L'Aguillas Bank, 
that the ftream of the current ftrikes ftrongeft jufl along the 
outer margin, which I fuppofe to have formerly been the old 
coaft of Africa, not only becaufe the foundings along this 
margin are deeper than on any other part of the bank, but be- 
caufe the bottom is fine white fand, fuch as is ufually found on 
the fea fhores ; and moft of the interior parts of the bank, and 
efpecially where it approaches the projeding points of the 
coaft, are compofed of rock, and the coarfe fragments of com- 
minuted fandftone. 
But the ftrong arguments advanced in favour of the Cape 
ifthmus having, at no great period of time, been covered with 
the fea, refts on the fea-ftiells that have been difcovered in the 
fand that is accumulated on its furface. Such fhells may exift, 
though I never faw them except on the fliores of the bays, but, 
as I have before obferved, whole ftrata of thefe may be found 
buried in the fides of the Lion's Hill, many hundred feet above 
the level of the fea. Thefe fhells have not been brought into 
that fituation by the waves of the ocean but by birds. There 
is fcarcely a ftieltered cavern in the fides of the mountains, that 
rife immediately from the fea, where livifig fhell fifti may not 
be found any day in the year. Crows even, and vultures, as 
well as aquatic birds, detach the fliell-fifti from the rocks, and 
mount with them in their beaks into the air ; fhells thus carried 
are faid to be frequently found on the very fummit even of 
the 
