J. Orton on the Andes of Ecuador. 245 
ally covered with snow. ‘ Chimborazo (said Humboldt,) is 
formed of one simultaneously uplifted mass of trachyte which 
has pierced, and reposes upon, secondary strata,” and Dauben 
adds that ‘‘ the trachyte dome was raised, and then the vol- 
canic fire was shifted to another quarter.” But to us the up- 
per third of the mountain appeared like a vast accumulation 
of volcanic matter ejected around and over a fissure in the up- 
turned metamorphic rocks of the Cordillera, The rounded 
contour of the trachytic beds, as well as their porous texture, 
Scrope contends, indicates their protrusion in an imperfect 
aio of liquidity. We observed the following rocks on Chim- 
Tazo ;* 
Fine-grained trachyte, gray, brown and dark colored (common.) 
= “soft, reddish, - 
Coarse, porphyroid trachyte, gray, a 
Cellular trachyte, iron stained, 
Compact trachyte, gray, 
F e-grained trachyte with seams of flint, 
sidian, 
it 
(rare.) 
ac 
ce 
Ob 
amile.+ The abyss is girt with a ragged wall of dark tra- 
chyte which rises on the inside, either vertically or at the an- 
gle of 50°. The outside of the cone agen is inclined 
i i ith fine 
| 
a 
5 
&. 
i=] 
oe 
pe 
eo 
j= 
re 
a2) 
=] 
S 
B 
— 
bo 
bd 
E 
i= 
5 
5 
fom 
* Complete series of the Rocks mentioned in this paper, are preserved in the 
- Cabinets of the Universite of Rochester, and of Ingham University, LeRoy, N. x 
hey were kindly identified by Dr. T. Sterry Hunt, F.R.S., the distinguished 
Mineralogist of the Canada Survey. ‘ a 
ina in Mexico, 2,000 foot Kighsr than. Pichincha, has a crater 6,000 
Wide, but only 500 feet deep. That of Kilauea is from 600 to 1,000 feet deep. 
____$ The author made two attempts to reach the botto: crater, the second 
of which was successful, Oct. 22, 1867. We were two in descending, 
8nd three hours in our exit. Mr. Farrand, a photographer, was the only Ameri-_ 
tan who had preceded us. 
