310 ANNUAL OF SCIENTIFIC DISCOVERY. 



EXPLORATION OF THE VOLCANO OF TICHINCHA. 



The following letter, descriptive of an exploration of the celebrated volcano 

 Pichincha, by M. Moreno, has been published in the Edinburgh New Philo- 

 sophical Journal : 



The short distance at which the volcano Rucu-Pichincha is situated from 

 Quito, has contributed to excite the curiosity of the scientific travellers who 

 have visited the territory of the Ecuador, and have caused the state and 

 form of the volcano to be well known. Bouguer and La Condamine, in 17 12, 

 were the first who reached the brink of the crater; Humboldt, in May, 1802, 

 twice surmounted the gigantic Avail of dolerite which forms the eastern 

 border of the volcano; and about thirty years after, Colonel Hall and M. 

 Boussingault followed in the same path; but since 1814, in which M. Sebas- 

 tin Wisse and I descended to explore it, no one had reached the bottom. In 

 August, 1845, we returned with the intention of making the topographical 

 plan of the volcano, measuring heights, etc.; and, in order that we might do 

 this, we had to pass three days and three nights in the two deepest cavities 

 which form Pichincha. 



This volcano forms two great basins, one on the east of the other, 4021 

 English feet in length. The eastern basin, called, without sufficient reason, 

 " Eastern Crater," has the form of a narrow valley, long and deep, through 

 the middle of which passes, from north to south, a fissure which receives the 

 rain and melted snow. There exists a slight depression in the upper part of 

 this basin, of an elliptical form, and perfectly horizontal at the bottom, 

 similar in everything to a little Alpine lake dried up by the action of the sun; 

 a depression which at one time, from its form, gave rise to the belief in the 

 existence of an inactive crater. The depth of this supposed crater is 1050 

 feet below the wall of eastern rocks; and as the highest of these reaches to 

 15,748 feet above the level of the sea, the height of the bottom of the eastern 

 crater is 14,698 feet. 



The western basin, or, more properly, the true crater of Pichincha, is one 

 of the most imposing objects which is presented to naturalists, and presents 

 the figure of a truncated cone placed upon its inferior base, which is 1476 

 feet in diameter, and rises in height to 2296 feet. Its depth from the eastern 

 side is enormous ; and gazing upon the immense towers of dolerite and tra- 

 chyte, elevated 2460 feet, sometimes vertically, sometimes in slopes more or 

 less steep and varied, an impression is received which can never be effaced. 

 Towards the western part, the height of the walls of the crater diminishes 

 gradually, leaving open to the east a fissure from whence the united waters 

 escape during the rains or thaws. 



In the middle of the inclined plain, which constitutes the bottom of the 

 volcano, the actual cone of eruption rises; it is 820 feet in diameter, 262 in 

 height above the bottom of the middle of the crater, and 13,707 above the 

 level of the sea, standing 4166 feet above Quito. This little mountain is now 

 the centre of volcanic activity in Pichincha, and presented in 1845 clear indi- 

 cations of remaining permanent many years without increase of intensity. 

 A great part of this mountain is covered with vegetation; two regions, part- 

 ing in opposite directions, completely gird it, until they are united in the 

 cleft of which I have spoken; and in the two points from whence the cone 

 of eruption is depressed (one to the centre, the other to the southeast), there 

 is given out in abundance a hot and sulphurous vapor, which lines with sul- 



