198 Elevation of Patagonia. pakt n. 



lowest and the uppermost plain, there is probably more 

 than one step-formed terrace : several measurements 

 show the existence of the intermediate one of the height 

 given in the diagram. 



Near the north headland of the great Bay of St. 

 George (100 miles south of the Chupat), two well 

 marked plains of 250 and 830 feet were measured: 

 these are said to sweep round a great part of the Bay. 

 At its south headland, 120 miles distant from the north 

 headland, the 250 feet plain was again measured. In 

 the middle of the bay, a higher plain was found at 

 two neighbouring places (Tilli Eoads and C. Marques) 

 to be 580 feet in height. Above this plain, towards 

 the interior, Mr. Stokes informs me that there were 

 several other step formed plains, the highest of which 

 was estimated at 1,200 feet, and was seen ranging at 

 apparently the same height for 150 miles northward. 

 All these plains have been worn into great valleys and 

 much denuded. The following section is illustrative of 

 the general structure of the great Bay of St. George. 



No. 16. 

 Section of Plains in the Bay of St. George. 



1,200 feet Est. Not measured. 



_ 580 An. IE, 330 An. M. 250 An. IT. 



Level of sea. Scale -^ of inch to 100 feet vertical. 



At the south headland of the Bay of St. George (near 

 C. Three Points) the 250 plain is very extensive. At 

 Port Desire (forty miles southward) I made several 

 measurements with the barometer of a plain, which 

 extends along the north side of the port and along the 

 open coast, and which varies from 245 to 255 feet in 



