406 Mr. E. Gibson on the Ornithology of 



boundary, again, is the Atlantic Ocean. The shore of the 

 latter is sand ; and a line of sand dunes (varying from half a 

 mile to two miles in width) extends from the cape down as far 

 south as the Sierras of Tandil, where the first rocks or cliffs 

 occur. The coast-line may be said to run north and south ; 

 but I am puzzled to account for the existence, inland, of nu- 

 merous long sandy ridges (now covered with grass) parallel to 

 each other and all trending N.W. and S.E. These would 

 seem to indicate that the action of the estuary of the River 

 Plate and the Atlantic Ocean combined have tended to alter 

 the shape of the cape since the formation of these old coast- 

 lines or beaches. 



Immediately inside the cape, and extending all round the 

 Bay of Sanborombon, the coast is of an entirely different 

 character. For three or four miles inland, and encircling the 

 whole of the bay, are found the '^ rincones,''^ a maze of islands 

 and peninsulas, formed of tidal creeks of more or less impor- 

 tance, the ramifications of which are innumerable. The 

 soil is a clay, hard enough on the surface, but becoming soft 

 as butter a few feet below the surface, and is strongly impreg- 

 nated with salt. The vegetation principally consists of dense 

 coverts of giant grasses, such as the pampa-grass [Gynerium 

 argenteum) and a species of esparto. The most of this land, 

 and all the tidal creeks, are inhabited by a small burrowing 

 crab, in countless myriads ; and the creeks are consequently 

 called " cangrejales " (from " cangrejo," a crab). The 

 " rincones " are evidently of very late formation, and are 

 perceptibly both rising and becoming firmer. 



The shore of the bay is muddy ; and various salt-water 

 carices fringe it in parts, from the cape upwards. A few rocks 

 of that curious formation known locally as " tosca " (the 

 " Loss " of the Pampean formation of German geologists) 

 make their first appearance also on rounding the cape and 

 advancing three or four miles into the bay. 



The camp ("el campo^^), or plains, are quite level in this 

 district, no roll in the prairie. Sir Francis Head, who, in 

 his ' Ride Across the Pampas,^ delineates them better than 

 any other writer I know of, gives a most graphic description 



