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PALEONTOLOGY: R. RUEDEMANN 5 
In South America, NW to W striking folds in rocks of Archean aspect north 
of the Amazonas and in middle and western Brazil are all of younger than 
Cambrian age. It is however possible that the N-S (NNE) direction of the 
folds of Archean rocks in the Sierra do Mar and S. de Mantigueira in east- 
ern Brazil can be correlated with the N-S folds in Africa and Australia. In 
Argentina, south of Buenos Ayres, mountain ranges composed of granite and 
gneiss with a SE strike represent, according to Suess, a continuation of the 
Brazilian basement complex. 
The Antarctic Continent has afforded rocks of Archean aspect and may 
represent another shield; so far, however, these rocks have been found only 
in loose blocks. 
The most important fact standing out from these data is that of the exist- 
ence of at least three vast areas of Pre-Cambrian rocks of a supercontinental 
order of size, with uniform structure. One of these comprises Eurasia, ex- 
clusive of India and parts of northern and middle Europe; another Africa, 
West Australia and possibly India and eastern Brazil; the third North Amer- 
ica with Greenland and the North Atlantic region to the Shetland Islands, 
but probably exclusive of the Colorado nucleus. 
It will be a matter of further inquiry whether these wide tracts of super- 
continental size that responded as units to the diastrophic forces that mark 
the world-wide Archeozoic and Algoman revolutions are to be considered as 
the first expressions of the gigantic continents that we find in Paleozoic time 
in the sense that they are ancestral or arch-continents. Indeed they well 
correspond to the later continents, as seen in the north Atlantic extension of 
North America across Greenland towards Europe; the Afro-Australian con- 
tinent (Gondwanaland) and the Eurasian continental mass of Paleozoic 
times (see paleogeographic maps by Lapparent, Freeh, etc.); the oceans that 
now separate the continents having arisen by a gradual collapse of the earth 
crust, probably along great circles. 
There is, however, this further possibility to be considered; that the NE 
and SE Pre-Cambrian fold systems of Eurasia and North America form one 
belt and the N-S fold system of the equatorial regions in Africa and Australia 
another one. In that case we should have, on the northern hemisphere, 
surrounding the North Pole, a continuous belt that consists of two pairs of 
directions, each composed of a NE and NW striking system of folds; the whole 
forming a zigzagged belt; and another belt of N-S folds approximately fol- 
lowing the equator. Between the two belts lie the independent blocks of 
India, Bohemia, Colorado, etc., all, or most of them with' a NE direction as 
if, in some way, leading from the equatorial belt up to the circumpolar belt. 
It will probably have to be left to future observations whether there are 
indications of a corresponding circumpolar belt on the southern hemisphere 
as slightly suggested by the occurrence in Argentina. 
If these belts actually exist as sketched here (see chart), then the question 
arises whether they do not represent cosmic agencies that influenced the 
