1884.] Microscopic Structure of some Rocks from Ecuador. 115 



Cotopaxi. 



" Two volcanoes in Ecuador Sangai and Cotopaxi are always in 

 a state of activity, and, of these two, the latter is the higher and the 

 more important mountain. Cotopaxi, according to my observations 

 with mercurial barometer on its summit, is 19,650 feet high, and it is 

 the second in altitude of the Andes of Ecuador, being inferior only to 

 Chimborazo. 



" It is situated approximately north-east of Chimborazo at a 

 distance of 65 miles, and lies south-east of Quito at a distance of about 

 32 miles. It is nearly due east of the Tinpullo ridge (11,550) over 

 which the road to Quito passes, and few mountains look so imposing 

 as it does from this direction the atmosphere of smoke and haze 

 which is always hanging about it, subduing its details without con- 

 cealing its general contour, produces an effect of stupendous size and 

 enormous height. 



" The volcano proper, as regards its north, west, and southern sides, 

 may be considered to rise from a plateau, which is elevated about 

 11,500 feet above the sea. I have only seen the eastern side from 

 considerable distances, and, as well as I can judge, the mountain 

 would appear to reach a lower level on the east than upon any other 

 side. No houses are, so far as I am aware, situated within 10 miles 

 of the crater the nearest, on the west, being at Santa Ana (10,335) 

 on the Qnito road ; on the south-west by west at the village of Mulalo 

 (10,036) ; and on the north-north-west at the hamlet of Pedregal 

 (11,628). 



" To judge correctly of the general form of this volcano, it is neces- 

 sary to view it at a considerable distance. At 15 miles, or further 

 away, the upper 8,000 or 9,000 feet present the appearance of a very 

 regular and slightly blunted cone. As the longer axis of the crater 

 has a northerly and southerly direction, the mountain looks sharper 

 when viewed from the north and south than it does when seen from 

 the west. The symmetrical appearance of the volcano diminishes 

 considerably upon a near approach, as its slopes are extremely rugged, 

 and its subordinate features acquire undue importance through the 

 effect of foreshortening. Although much snow falls upon the upper 

 4,000 or 5,000 feet of the mountain it seldom wears a snowy aspect, 

 through the ash which is continually being ejected quickly blackening 

 it, and from rapid liquefaction, owing to the warmth of the cone. 



" With the view of inspecting the interior of the crater (respecting 

 which apparently contradictory accounts had been given by those 

 who had previously ascended the mountain), I proposed to encamp 

 close to the summit, in order that we might see the crater by night. 

 The first day's march took us from the town of Machachi (9,850) to 

 the hamlet of Pedregal (11,628), and the second day to the lower 



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