GREAT BASIN OVERTHRUSTS 
253 
EDITORIAL 
Ove:rthrusts in Gre:at Basin Rangks 
When, several years ago, the fault-block hypothesis of Desert 
Range structure was challenged, multiple origin was premised and 
a possible genesis of some of the mountain ridges through over¬ 
thrust was intimated. Since that date some specific examples 
were disclosed. The evidences seemed so clear as to invite re¬ 
newed search for similar and critical phenomena. Reason offered 
by the most ardent advocates of the normal fault-block hypothesis 
for not finding a single fault-line during a whole half century, 
was that the displacement lines must be deeply covered by pied¬ 
mont waste, because the mountains were buried up to their should¬ 
ers in their own debris. 
On the other hand, according to the erosional theory of Desert 
Range origin, the mountains were deeply girdled through wind- 
scour. Any fault-lines which may have once existed were now 
far out on the adjoining plains, where they were obscured or com¬ 
pletely hidden by the desert soils. 
In another direction, if the displacements were thrusts, the 
plains were not yet always removed down to the proper level to 
reveal the fault-lines. But with this idea as a clue some move¬ 
ment planes, notwithstanding the fact that they probably did not 
really have anyhing to do with moulding the stature of the present 
mountains, were finally unearthed. 
Genesis of the Desert Ranges of the Great Basin is variously 
interpreted. According to fundamental differences the several 
hypothesis fall into four sharply defined categories. All are tec¬ 
tonic in nature, except the last. The differences are contrasted 
in the following tabulation, which is modified somewhat from the 
similar one which was published in the Bulletin of the Geological 
Society of America, a few years ago. 
