268 
ELDRIDGE. 
the forces uplifting the range were generated, although not 
accepted by all scientists, does, nevertheless, more completely 
and satisfactorily fall in with the observed facts than any 
other which can be suggested. It is not intended, however, 
that this shall preclude the acceptance in the future of any 
other grounds upon which it may be possible to establish a 
still more satisfactory explanation of the phenomena form¬ 
ing the subject of this paper. 
2d. Manner in which the forces of deration have locally 
manifested themselves. —At various points along the base of 
the Colorado Range occur strongly pronounced local pecul¬ 
iarities of structure, either faults, or folds of varying shape 
and character, both secondary as to the general uplift of the 
range. It is highly probable that these structural peculiari¬ 
ties are attributable to the general forces of elevation that 
are acknowledged to have been in action through the several 
geological periods here represented. 
3 d. The unequal distribution of, or resistance to, the general 
force of elevation. —Still further, it may unhesitatingly be 
granted that the general force of elevation or the resistance 
opposed to it has been more or less unevenly distributed 
from point to point, and has acted, not always at an abso¬ 
lutely right angle to the axis of the range, but diagonally to 
it, in one or more directions at the same time. Its direction 
has in fact varied according to circumstances. 
Ath. The development of the post-Niobrara fold. —In the 
present area the distribution and directions of this force up 
to immediate post-Niobrara time had been such as to eventu¬ 
ally bring into existence the fold of the general character 
represented in the profiles, and in figure 1 beyond. 
An analysis of this distribution and its effects shows that, 
of the various components of this force, the major, which ex¬ 
ceeded all the others combined, was that acting in the gen¬ 
eral elevation of the range and directly against its axis— 
that is, for the eastern base, with the arrows A (Fig. 1) west¬ 
ward. This had undoubtedly been in action with probably 
but little interruption from earliest time. The other com- 
