POSITIONS OF ANCIENT CONTINENTS 367 
POSITIONS OF THE ANCIENT CONTINENTS 
By Dr. Rudolf Ruedemann 
New York State Museum 
From the preparation of palegeographical maps of times before 
the Cambric Period paleontologists invariably shrink. Absence 
of fossils record shrouds that distant period in an impenetrable 
obscurity. But the uncertainty of the twilight is not nearly so 
deterring now as some paleogeographers would have us believe. 
Fossils are no longer the sole, or indespensible, guides in the 
geographic excursions into times v/hen the earth was young. 
Difficulties with the metamorphic and non-fossiliferous rocks 
are rapidly growing less formidable. Little by little perplexities 
once thought unsurmountable give way. Distinction among Pre- 
Cambrian beds of originally marine and terrestrial formations give 
up their criteria for classing them as deep-sea or continental ter- 
ranes. Folded and foliated, faulted and intruded massifs which 
once furnished no distinctive lines of attack, now permit of reason¬ 
able interpretation. Even intercontinental correlations, formerly 
so impossible, begin to assume orderly position. The ground is 
now not nearly so uncertain as it was even a short while ago. 
In briefly summarizing the data that may be competent to indi¬ 
cate the configuration of the Pre-Cambrian land-masses it must 
also be asked whether the world-wide folding of the Archean 
basement complex could not be explained by simple terrestrial 
forces. In this connection the result of close mapping of the Pre- 
Cambrian folds, carried out in late years, in Bohemia and Scandi¬ 
navia is of great importance. It brings out closely compressed 
folds whose strikes are tortuous and wavy curves and often sub- 
circular and even angularly broken lines. This, it has been con¬ 
cluded, points to a tangential pressure, acting from all sides on an 
