284 
During the early part of Paleozoic time continental con- 
ditions prevailed in South Greenland. Long continued erosion 
removed all the rocks which originally covered the Julianehaab 
granite, and the surface of the country gradually assumed the 
character of a peneplain. Probably in late Silurian (or Devo- 
nian) times the conditions were changed, a subsidence occurred, 
and the Zgaliko sandstone was laid down upon the granite. 
That the condition of the surface, before the deposition of the 
sandstone, was at least partially that of a peneplain, is indicated 
by several facts: — (1) as far as has been observed, the upper 
sandstone covered surface of the granite is almost level and 
parallel to the bedding planes of the sandstone; (2) a layer 
of arkose generally of considerable thickness immediately over- 
lies the granite; (3) the conglomerate beds of the sandstone 
are almost exclusively made up of sandstone pebbles. 
The Igaliko sandstone for reasons given (p. 18) is supposed 
to be Devonian. Except where metamorphosed it is red stained 
throughout. Perhaps it is largely of æolian origin, but since 
conglomerate beds with large and well-rounded sandstone peb- 
bles are intercalated at several horizons, wave action must at 
intervals have played an important part in its formation. The 
total thickness of the sandstone is about 1200 meters. 
The sandstone is overlain conformably by a series of vol- 
canic sheets: diabases, porphyrites, and porphyries. The ques- 
tion whether the volcanic activity immediately succeeded the for- 
mation of the sandstone, or not, has not been definitively settled. 
Certain observations mentioned in the second chapter tell in 
favour of the view that the conditions of sedimentation which 
gave rise to the red sandstone, continued after the beginning of 
the volcanic activity, and the second igneous epoch in South 
Greenland is for this reason believed to have commenced in 
late-Devonian times. 
This period of igneous activity was no doubt a long one, 
and it showed considerable intensity. The total thickness of 
