3o6 TJic A^ncncan Geologist. May, i898 
granite rest on it. Hence this beach, too, is to be attributed 
to the glacial period. At about the same elevation, between 
fifty and seventy metres, similar terrace lines are to be found 
at many places in the archipelago, pointing to a higher water 
mark in earlier times. 
lielow this mark there are to be found in many parts of 
the valleys stratified formations usually of clay. These are 
vary scarce in fossils, though they have on examination been 
proved to contain marine Diatomaceae and sponge spicules. 
A remarkable feature of the whole district is the immense 
size and development of the valleys. In relation to the rivers 
flowing through them, these valleys are mostly broad, with lofty 
and steep though not perpendicular walls. Down below, 
through a quite level country, the river slowly makes its way 
in complex snake-like meanderings. This state of things 
recurs in the mountain district of the Cordilleras and in the 
Quaternary and Tertiary elevated plains of the Pampas. 
To now pass the development of the Magellan Territories 
during the most recent geological phases in review : 
During the Santa Cruz period that, according to recent 
inquiries corresponds approximately with the Miocene period 
in the north, a wide continent already existed here, probably 
forming a low, marshy country with numerous fresh-water 
lagoons on its surface. The country was overgrown with 
extensive forests, at that time as at the present principally 
species of the beech, but also with Araucaria and other varie- 
ties. These forests were the abode of strange beasts, Hom- 
unculus, Xylotherium, Typotherium, Macrauchenia and many 
others. The climate was warmer and more humid than at 
present, though by no means tropical. 
Thereupon, came in the Pliocene period a depression ; the 
present coast territories, at any rate, were below water, in 
which at that time the fauna of the Cape Fairweather dwelt, 
forms, of which some still exist in those regions, while others, 
for instance certain large varieties of Ostrea, are extinct. 
It is possible that contemporaneously an elevation took 
place in the west, for otherwise it is difficult to explain the 
phenomenon that thereupon ensued. Enormous quantities of 
ice collected in the Cordilleras; they did not, it is true, stretch 
far across the plain to the east, but they brought down, in the 
