120 M. Humboldt on the Sulphur Mountain of Ticsan. 



schist from 70° to 80° to the north west. The bed of quartz, 

 which passes sometimes into the hornstone, is wrought in an 

 open working. The dechvity of the Cerro Qiiello, on which 

 the works were begun some centuries since, is opposite to 

 the south-south-eust ; and the bed of quartz appears to be 

 prolonged towards the north-north-west, that is to say, to- 

 wards the coast of the Pacific Ocean. It is however asserted 

 that sul})]uu' has not been found on the surface of the ground 

 in this direction to the distance of 2000 toises from Ticsan. 

 All is covered there with a thick vegetatioii. Towards the 

 end of the eighteenth century, masses of sulphur were still 

 worked, which were from 2 to 3 feet in diameter. At present 

 they are working some quartzose strata much less lich, in 

 which the sulphur is only dispersed in nodules from 3 to 4 

 inches thick. It is observed that the quantity of sul))hur in- 

 creases with the depth ; but the working has been so unskil- 

 fully directed that the lower strata are nearly inaccessible. 

 The quartz in which the sulphur is dispersed presents neither 

 ^reat fissures nor cavities, or druses ; nor have I been able 

 to find any specimen of crystallized sulphur. 



The mineral which is the object of the working of the Cejio 

 Qiicllo does not form a mass or complication of veins, as might 

 be supposed : the sulphur is dissemuiated without any con- 

 tinuity by little masses in the quartz which traverses the mi- 

 caceous schist in a direction parallel to its strata. The clefts 

 that have perhaps formerly united these masses are no 

 longer visible, but all the quartz seems to have undergone 

 an extraordinary change. It is tarnished, often brittle, 

 and breaks in some parts on the least shock ; which indicates 

 an imperceptible cleavage. The temperature of the rock 

 did not differ from that of the exterior air. The inha- 

 bitants like to attribute the violent earthquakes to which their 

 country has been sometimes exposed to concavities which 

 they suppose to exist under the mountain of sulphur. If this 

 hypothesis be well founded, it must be admitted that the cause 

 which it indicates acts but locall}'. In the great catastrophe 

 of the 4th of February 1797, which destroyed so many thou- 

 sand Indians in the province of Quito, — the three places where 

 there is the most sulphur, the Cerro Quello, the Azufral of 

 Cuesaca near to the Villa of Ibarra, and the Machay of Saint- 

 Simon, near the volcano of Antisana, were but very feebly 

 agitated ; but at a much earlier period there has been ex- 

 perienced, even on the bed of quartz which includes the sul- 

 phur near Ticsan, an explosion similar to that of a mine. 



The bed of quartz appears at the surface on the two sides of 

 the little river of Alausi; and facing the Cerro Quello is 



found 



