212 Uniform Height of Terraces, part u. 



ingly tabulated all those which represented the sum- 

 mit-edges of plains. The extension of the 830 to 355 

 feet plain is very striking, being found over a space of 

 500 geographical miles in a north and south line. A 

 table of the measurements is here given. The angular 

 measurements and all the estimations are by the Officers 

 of the Survey ; the barometrical ones by myself : — 



Feet. 

 Gallegos River to Coy Inlet (partly angular meas. and partly . 



estim.) . . . . . " 350 



South Side of Santa Cruz (ang. and barom. meas.) , . . 355 



North Side of do. (ang. ni.) 330 



Bird Island, plain opposite to (ang. m.) 350 



Port Desire, plain extending far along coast (barom. m.) . . 330 

 St. George's Bay, north promontory (ang. m.) .... 330 

 Table Land, south of New Bay (ang. m.) 350 



A plain, varying from 245 to 255 feet, seems to 

 extend with much uniformity from Port Desire to the 

 north of St. George's Bay, a distance of 170 miles; 

 and some approximate measurements, also given in the 

 following table, indicate the much greater extension of 

 780 miles:— 



Feet. 

 Coy Inlet, south of (partly ang. m. and partly estim.) 200 to 300 

 Port Desire (barom. m.) ..... 



C. Blanco (ang. m.) 



North Promontory of St. George's Bay (ang. m.) 

 South of Xew Bay (ang. m.) .... 



North of S. Josef (estim.) 



Plain of Bio Negro (ang. m.) .... 

 Bahia Blanca (estim.) 



245 to 255 



250 



250 



200 to 220 



200 to 300 



200 to 220 



200 to 300 



The extension, moreover, of the 560 to 580, and of 

 the 80 to 100 feet, plains is remarkable, though some- 

 what less obvious than in the former cases. Bearing 

 in mind that I have not picked these measurements 

 out of a series, but have used all those which repre- 

 sented the edges of plains, I think it scarcely possible 

 that these coincidences in height should be accidental. 

 "We must therefore conclude that the action, whatever 

 it may have been, by which these plains have been 



