250 J. Orton on the Andes of Ecuador. 
@ 
i=) 
e 
" 
_ 
or 
S 
& 
ro 
= 
© 
5 
5, 
om 
— 
9°) 
pl 
ef 
ae 
~ 
° 
i) 
=] 
be 2] 
o> 
eo 
=] 
ae 
<< 
&. 
io") 
is] 
or. 
B 
OS 
» 
i? 2] 
a 
a 
J 
ce 
From these examples it will be seen that the products of — 
the Ecuadorian volcanoes are mainly feldspathic, Trachyte 
abounds throughout the Andes. All the summits which rise 
above the limit of perpetual snow are trachytic. The trachytes 
of Bolivia, says D’Orbigny, are always micaceous ; those 0 
the equator are cellular, porous, granitoid, granular or com- 
pact. Cotopaxi alone produces foam-like pumice. * most 
perfectly glassy translucent obsidian is occasionally found on 
Cotopaxi and Chimborazo. Its sp. gr. is 2°35 to 2°40, _Hum- 
boldt mentions pitchstone as occurring on Antisana, There 
pele rphyries in containing . 
mica. The absence of basalt as well as the paucity of quart® 
uw America, are rarely visible on the Pacific side, in th 
< aT 2 ; ? ‘eS 
neighborhood of volcanoes, B e 
i unto in the employ of Ecuador, claims the discovery cae 
the solution and removal of oleanic fusion, but simply a rock altere’ 
hive 
