208 Concluding Remarks on the paet n. 



along the eastern coast of Tierra del Fuego : at two 

 places here, 110 miles apart, this plain was found to be 

 950 and 970 feet in height. 



From Coy Inlet, where the high summit-plain 

 trends inland, a plain estimated at 350 feet in height, 

 extends for forty miles to the river Gallegos. From 

 this point to the Strait of Magellan, and on each side 

 of that Strait, the country has been much denuded and 

 is less level. It consists chiefly of the boulder forma- 

 tion, which rises to a height of between 150 and 250 

 feet, and is often capped by beds of gravel. At N.S. 

 Gracia, on the north side of the Inner Narrows of the 

 Strait of Magellan, I found on the summit of a cliff, 

 160 feet in height, shells of existing Patellas and Mytili, 

 scattered on the surface and partially embedded in 

 earth. On the eastern coast, also, of Tierra del Fuego, 

 in latitude 53° 20' S., I found many Mytili on some 

 level land, estimated at 200 feet in height. Anterior 

 to the elevation attested by these shells, it is evident 

 by the present form of the land, and by the distribution 

 of the great erratic boulders x on the surface, that two 

 sea-channels connected the Strait of Magellan both 

 with Sebastian Bay and with Otway Water. 



Concluding remarks on the recent elevation of the 

 south-eastern coasts of America, and on the action of 

 the sea on the land. — Upraised shells of species, still ex- 

 isting as the commonest kinds in the adjoining sea, occur, 

 as we have seen, at heights of between a few feet and 410 

 feet, at intervals from latitude 33° 40' to 53° 20' South. 

 This is a distance of 1,180 geographical miles — about 

 equal from London to the North Cape of Sweden. As 

 the boulder formation, extends with nearly the same 

 height 150 miles south of 53° 20', the most southern 

 point where I landed and found upraised shells; and 



1 ' Geolog. Transactions,' vol. vi. p. 419. 



