POSITIONS OF ANCIENT CONTINENTS 373 
times of greater diastrophic events. This is, at least, strongly urged 
by the evidence of the great widely spread Pre-Cambrian uncon¬ 
formities that separate the different formations, both here and in 
the old world. 
The evidence of repeated periods of wide continental elevation 
in Pre-Cambrian time that is afforded by the major unconformities 
is corroborated by the recognition of Proterozoic glaciation, not 
only on the Canadian shield, but also in Scotland, the Baltic shield. 
South Africa, India, South China, South Australia, and Tasmania. 
The great Pre-Cambrian continental mass of the southern hemi¬ 
sphere which the Pre-Cambrian folding, by its continuous north- 
south folding, indicates to have extended from Africa over Mada¬ 
gascar to Middle Australia and East India — and if the folds of 
eastern Brazil and eastern Australia are posthumous in character, 
also to these regions — is the evident ancestor of the great Gond- 
wanaland. Gondwanaland had its most glorious geologic period 
in Carbonic to Triassic times when it extended, as a separate 
continental mass, from western South America across Africa to 
South Asia and beyond Australia. This vast continent with its 
characteristic flora and glacial period reached in Permian time 
in east-west direction two-thirds around the world. It broke 
down in the middle, where the Indian Ocean now is, in Jurassic 
time, and Africa, East India, Australia and a large portion of 
South America are its remnants. 
Clarke has shown that Gondwanaland existed in Devonic time, 
but was then connected with Antarctica, and has therefore pro¬ 
posed the name “Falklandia” for this earlier continental mass. 
The evidence from the uniform direction of the Pre-Cambrian 
folds proves, in our view, that like the two northern continental 
segments, also the southern unit Gondwana was inherited from 
Pre-Cambrian time and persisted throughout Paleozoic time; for 
the Cambric, Ordovicic and Siluric periods were clearly such of 
land and of epicontinental seas over the three southern continents. 
This is indicated principally by the total absence of their rocks 
over most of these three continents of today; or where the rocks 
are present, by their fossil and lithic facies. Parts may have been 
temporarily invaded, as central Australia and a large part of the 
present Indian Ocean, during Cambric time, but such facts as the 
