74 
OROGENY AND EARTH’S ROTATION 
ing out of the originally moist condition, the layers of paper local¬ 
ly buckle. Ordinarily this yielding would take place outwardly, 
but the strong firmly glued wrapper prevents relief in that direc¬ 
tion. The net result is that there is a notable flexing inward, a 
folding so sharp at times that if the paper were not so tough, but 
brittle instead, rupture, or to use the strictly geological term, typi¬ 
cal faulting would insue. 
By the use of layered materials not so tough as paper character¬ 
istic faulting phenomena no doubt would also develop. Were 
the straticulate shell of the roll, or spheroid, so constructed as to 
provide a texture and arrangement of the component layers more 
nearly corresponding to the conditions found in nature ac¬ 
quired orographic structures would unquestionably result as per¬ 
fect as any displayed anywhere in the world. This is readily ac¬ 
complished by a little prior calculation of relative rigidity and 
viscosity values of the materials used, and by the exercise in the 
experiments of a little ingenuity in the selection and arrangement 
of the layered masses. Under these circumstances one would 
expect structural replicas of all of the great earth-wrinkles. How¬ 
ever, the chief interest in the recent experimental results lies in 
other directions. 
The physiognomy of the continents, with their mountainous 
borders and broad sea-level interiors, as so strongly emphasized by 
Dana, as an essential continental characteristic, finds curious re¬ 
production in experiment. The fact that this plait of the first 
order is not an occasional production but an almost invariable 
result is highly significant. It points to the feature as being a 
necessary consequence of stress release. By analogy a similarity 
of genesis in terrestrial structures is inferred. 
That the formation of the continental plait is capable of exact 
reproduction in the laboratory is a fact quite extraordinary (figure 
4.). Even more remarkable is the diagrammatic idealism which 
the experiments portray, presenting vertical exaggeration not to 
be found in nature. Fondest expectations in the laboratory would 
hardly hope for such an exact counterpart of the North American 
continent, bordered on either margin by lofty ridges. 
Not less noteworthy than the reproduction of the typical con¬ 
tinental plait is the frequent and simultaneous development in the 
paper-roll of three compound plaits unequally spaced around the 
