2 
PALEONTOLOGY: R. RUEDEMANN 
in some cases the new folds have clearly followed old lines of folding (post- 
humous folds). There are further left, even in those regions that were 
overrun by the crustal waves of Post-Cambrian time, 'islands' or blocks 
that remained undisturbed and that give important information on the orig- 
inal direction of folding in the Pre-Cambrian basement complex. Such un- 
disturbed blocks are found in the Rocky Mountains, in Bohemia, on Borneo, 
in Cambodia, etc. 
The large areas that are then left and lend themselves to our inquiry, are 
the greater part of North America, small regions of South America, eastern 
Europe, northern and eastern Asia, all inner Africa and western Australia. 
The general facts gleaned from them are complemented by those obtained 
from the unfolded 'islands' or blocks. 
The most important of these areas are the so-called continental nuclei of 
North America (Canadian shield), Europe (Baltic shield) and Asia (Angara 
shield). An intended comparison of their principal directions of folding 
presupposes essential contemporaneity of the diastrophic revolutions they 
have undergone. This has been established by the correlations carried out 
by Adams, Sederholm and Willis. It is also to be noted that evidence of a 
like succession of eras and diastrophic events has been found in most of the 
other regions here mentioned as being amenable to our inquiry. 
The source for this inquiry is chiefly Edward Suess ' The Face of the Earth, 
where there is not only a large store of information as to the directions of 
Pre-Cambrian rock folding but where also the facts of the general directions 
of Pre-Cambrian folding in Asia and eastern Europe are clearly set forth. 
Nevertheless the assembling of the full data on Pre-Cambrian folding, which 
will be given in a later publication, requires laborious search through a widely 
extended literature. 
With these introductory remarks we may briefly survey the preliminary 
results (which undoubtedly are still subject to important corrections) as to 
the arrangement of Pre-Cambrian folds. 
In China, Richthofen, Pumpelly and Willis have found a uniform NE 
direction in the basement complex, which was completely folded and again 
abraded before the Cambrian submergence. This NE direction (the Sinian 
system of Richthofen and Pumpelly) continues through Korea, and Suess 
has shown its complete domination in all northeastern Asia east of Lake 
Baikal (his 'Baikal direction'), which is ENE-NE. This meets, in a merid- 
ional line, the 'Sajan direction' of Pre-Cambrian folds, which is WNW to 
NW and prevails west of Lake Baikal through all northern and middle Asia, 
Russia (Karpinski) and the Baltic shield, the latter being only a larger north- 
ern exposure of the Russian Pre-Cambrian plate. The latter extends through 
northern Europe much disturbed by later folding and probably abuts against 
the Laurentian plate in western Scotland. 
In North America the Canadian shield exhibits in its eastern portion a 
uniform NE direction of the folds (Adams and Coleman). This direction 
