31 S Professor Jameson on Hocks formed hy Hot Springs^ 
3. Rocks formed hy Torrents of Mud flowing from Suhterror- 
nean Lakes. 
In the interior of volcanic mountains, there sometimes occur 
caverns or hollows partly filled with water, thus forming subterra- 
nean lakes. The earthquakes that often agitate these mountains, 
are occasionally so violent, as to produce great rents, which give 
free passage to the water of the lakes, which bursts forth with 
tremendous violence, deluges the neighbouring country, and 
covers it to a greater or less extent, and with a more or less deep 
crust of muddy matter. In the earthquake of the year 1716, 
which overturned Lima, four volcanoes opened at Lucanas and 
in the mountains of Conception, and occasioned frightful de- 
luges. The volcanoes of the kingdom of Quito sometimes ex- 
hibit phenomena of the same kind, but accompanied with cir- 
cumstances so extraordinary, that we shall now state them. 
The enormous volcanic cones of Cotopaxi, Pichincha, Tun- 
gouragua, &c. in South America, never throw out lava, but 
frequently ashes, scoriae, and pumice, and sometimes vomit 
forth immense quantities of water and mud. These eruptions 
take place more frequently from the sides than from the craters - 
of the volcanoes, and the muddy waters appear to be derived 
from lakes situated in the interior of the mountains, which Kirst 
forth with incredible fury, when any accidental cause, such as 
an earthquake, splits, and thus opens the side of the mountain. 
In the year 1698, the mountain of Carguarazo, near to Chim- 
boraco, fell down and covered eight square leagues of country 
with mud. In the earthquake of the 4th February ITOl, 
40,000 persons were destroyed by eruptions of water and mud, 
(moya). Muddy waters, resembling those which flow from 
volcanic mountains, are vomited forth in great quantity, from 
districts where no volcanic rocks occur, when these are agitated 
by earthquakes or other causes. In Peru and Quito, the deva- 
stations occasioned by volcanoes are not caused hy streams of 
lava^ but by water and enormous streams of mud. This sub- 
stance, which at first has only the consistence of homll% but soon 
hardens on exposure, is named Moya. It presents two remark- 
able phenomena, viz. an intermixture of -inflammable matter 
and of fishes. The inflammable matter is so abundant that the 
