TRANSLATIONS AND NOTICES 



GEOLOGICAL MEMOIRS. 



Exploration du Volcan Rucu-Pichincha (Quito). Par MM. Seb. 

 WissE et Garcia Moreno, dansle mois d'Aout, 1845. Abridged 

 from the Comptes Rendus, 184^6' 



PiCHiNCHA is situated eleven miles in a straight line W.N.W. from 

 Quito : its sides, which are covered with vegetation to the height of 

 12,116 feet, are furrowed by deep ravines. All the part above, 

 called the ' Arenal,' is covered with sand and pumice, and is inclined 

 at an angle of 25° to 35''. 



The authors having ascended the Arenal to the height of 1542 feet, 

 reached the edge of the crater, which is broken down on the south 

 and on the west, and found the cavity of the volcano to consist of 

 two funnel-shaped craters, apparently resulting from two sets of 

 eruptions. They descended into the eastern crater, a depth of 

 1050 feet, and found it to consist simply of a vast ravine, at the 

 bottom of which was the bed of a torrent, always dry except during 

 rains. 



The western crater is nearly circular, and regularly funnel-shaped : 

 at the bottom is a small plain, through which flow two torrents, which 

 unite near the western opening of the crater. On the western side 

 of this plain rises a hill or cone of eruption, whose height is about 

 260 feet above the mean level of the bottom of the crater, and its dia- 

 meter about 1476 feet. This hill is embraced by the two torrents, so 

 as to form a kind of peninsula during heavy rains. It is far from per- 

 fectly conical at present, being covered with irregular heaps of stones, 

 and fissured in all directions, proving the violence of the convulsions 

 it has been subjected to in recent times. The volcanic vents, whether 

 active or extinct, are all situated in this cone of eruption ; not the 

 slightest trace of one being found elsewhere. They are arranged 

 in nearly circular groups of different dimensions, some of them at- 

 taining a diameter of 82 feet. There are in all nine of these groups, 

 six in activity and three extinct, all situated in those parts of the 



VOL. III. PART II. D 



