GREAT i;XTEST OF TITE TALLEYS. 
365 
Eio Necrro (lat. 38°-39®) groups of mountains seem to rise 
in the form of islands, in the middle of a muriatiferous plain. 
A tribe of Indians of the south ('rehuellet), have there long 
borne the characteristic name of “ men ot the mountains 
(Callilehct) or Serranos. From the \ f 
the Eio Negro to that of Cabo Blanco (lat. 41 -47 ), scat- 
tered mountains on the eastern Patagonian coast denote 
more couaidcrablc inequalities inland. All that part, hoT - 
ever, of the Straits of Magellan, from the Virgins Cape to 
the North Cape, on the breadth of more than SO leagues, is 
surrounded by savauiiahs or Pampas ; and tbe Andes of 
western Patagonia only begin to rise near the latter cape, 
exercising a marked intlncnce on the direction of tliat part of 
the strait nearest the Pacific, proceeding from S.K to N.W 
If we have given the plains or groat b.isiiis of South 
America the names of the rivers that flow in their longi- 
tudinal farrows, we have not meant by so doing to compare 
the i^to mere valleys. In the plains of the Lower Orinoco 
and the Amazoii, ail.the lines of the declivity doubtless reacb 
a principal recipient, and the tributaries of tributary streamy 
that is the basins of dillerent orders, penetrate far into the 
oToup of the mountains. The niiper parts or high \allejs of 
the tributary streams must be considered in a geological 
table, as belonging to the mountaiiious region of the country, 
aiidbeyond the plains of the Lower Orinoco and the Amazon. 
The viws of the geologist are not ulcntical wnth those of the 
hydi’ographer. In the basin of the Kio de la Plata and Pata- 
Sniiq^thc w aters that follow the lines ot the greatest declnn- 
ties have many issues. The same basin contains seieral 
valleys of rivers ; and when we examine nearly the polyediic 
surface of the Pampas and the portion ot their waters which, 
like tlie waters of the steppes of Asia, do not go to the sc-i, 
we conceive that these plains arc divided by snia 1 ridges oi 
lilies of elevation, and have alternate slopes, iiudmed with 
reference to the horizon, in opposite directions. In order to 
point out more clearly the dilVerciice between 
hydro^raiihic views, and to prove that in the former, abstraet- 
irt^e cLrse of the watoi4 which meet in one recipient, we 
oitai fa for more general ,.oint of view, 1 shall here again 
ScTto he l^-drographic’ basin of the Orinoco. That im- 
mZe river risL on"thc. southern sloiie of the bierra larime 
