114 Ascent of the Volcano of Popocatepetl. (February, 
moraine as would have been desirable, but in one instance the 
moraine was composed of the fine mud scrapings of the lava with 
rounded boulders of basalt of all sizes up to four or five feet in 
diameter, the hill being covered with wheat and smal) corn. 
Moreover the hills above the moraines on each side of the valley 
had apparently been molded by ice. I infer from all I saw on 
the ascent that the ice must have filled the valley or pass between 
Iztacihuatl and Popocatepetl, spreading out over the plateau like 
a mer-de-glace and sending glaciers down to the lakes then cov- 
ering the plains of Anahuac. Above the rounded hills were 
rough volcanic spurs and hills which may once have overlooked 
the ice streams. 
It would appear, then, that the Quaternary lakes of the Mexi- 
can plateau (unmistakable evidences of which I saw throughout 
the country from Laredo to San Luis Potosi, and thence to the 
City of Mexico, as well as along the Mexican central route 
to New Mexico) were fed by the melting of glacial ice in the 
high sierras. At any rate in the valley of Anahuac the volcanoes 
rising above it must have been covered with glaciers which de- 
scended to a point gooo feet above the sea, and about 1000 
feet above the present level of the plains. 
The change in vegetation as we left the plains and wound 
among the moraines was an interesting feature of the ride. The 
zone of cactus, nopal, mesquite, etc., of the Mexican plateau was 
replaced by a belt of pines, aromatic firs and cedars; the flowers 
had changed in character and become more numerous and varied 
than on the dry and dusty plains ; lupines predominated, relieved 
by a showy red labiate flower and yellow-flowered shrubs. Of 
1 In conversation with Mr. Otto Finck, to whom I described the moraines about 
Popocatepetl, he told me that what he regarded as true glacial moraines extended 
down along the route of the Mexican railway as far as Peñuella, which is three miles 
east of Cordova, and is 2500 feet above the sea, Cordova being 2700 feet elevation. 
I had seen boulders of porphyry above the city of Orizaba, and Mr. Finck, who is 
an observer of long experience in the State of Vera Cruz, having explored the 
country for hundreds of miles on foot, and being a naturalist of experience, kindly 
‘took me down to the bed of the river, where were boulders of different kinds of 
hyry, evidently derived from the plateau above and westward. On the plains 
of Jaumatlan and Chocaman, he told me, are boulders of porphyry, weighing 200 . 
tons, and also glacial scratches. Mr. Finck drew for me a section of what he re 
_ garded as a moraine observed at the Pass of Metlac, in which were angular blocks 
of porphyry of ten or twelve kinds, with gneiss, which must have been transported 
from the plateau above. Below an elevation of 2500 feet Mr. Finck had not in thë 
State of Vera Cruz, or elsewhere in Mexico, observed any glacial marks. 
al E 
