Foerste.] 
408 
[April 6, 
cracks ever existed, the streams must at once have occupied the 
lowest levels of the cracks, and since that time the streams must 
have been deepening their channels below the lowest points to 
which the cracks extended ; in that case it would not be likely 
that any indications of the former gaping cracks could still be 
found. Geologically it would be difficult to disprove such a 
theory, no matter how clearly all existing evidences might point 
to the present non-existence of fractures of any structural import- 
ance. Considerations of this kind were constantly forcing them- 
selves upon my mind, and tempting me to believe in theories of 
fracture, even after I had satisfied myself that there was no evi- 
dence in favor of this view. 
8d. Lowest Points of Outlets for Lakes. (See PI. XI.) It is well 
known that the bottoms of synclinal valleys usually do not main- 
tain the same level or preserve the same pitch throughout their 
entire length. In a similar way the heights of the folds on either 
side are known to vary. It is readily possible therefore that, 
where two pitches from opposite sides of the same synclinal valley 
meet, lakes may accumulate. Should these lakes attain sufficient 
height, they might overflow at either end, or, in case the elevation 
were lower, find an exit across some point along one of the folds 
bounding it on either side. In this second case, an outlet once 
formed might in the course of time cut out a cross valley of suffi- 
cient depth to drain the lake, and develop itself into a cirque. 
There are, however, several reasons why this theory is very im- 
probable in the case of the Bernese Jura cirques. 
First. In the case of the Boujean, Court, and Moutier cirques 
it is evident that there were lower points of outflow than those 
furnished by the crests of the folds where the cirques now are. 
Thus the highest point of the synclinal valley northeast of the 
Boujean cirque is 724 meters. The elevation of fold at tli ^cirque 
was at least 800 meters, and probably exceeded 900 meters. The 
highest point in the valley between the Moron and the Graitery 
fold is 855 meters, while the elevation of the fold at the Court 
cirque was at least 1,050 meters, and probably much more. The 
highest point in the valley northwest of the Moutier cirque , be- 
tween the Roche fold and its Raimeux branch, is 746 meters, 
while the elevation of the fold at the Moutier cirque was at least 
800 meters, and probably exceeded 900 meters. 
Second. It is inadmissable to suppose that the Court and 
Moutier cirques could represent lowest points of outflow for lakes, 
