66 
OROGENY AND EARTH’S ROTATION 
amine in detail the characteristics of the fault-lines bounding the 
orographic blocks. When repeated and diligent search failed to 
disclose the presence of a single fault-plane even along the line of 
the so-called fault-scarp at the base of the mountain ridges it was 
still long before it was suspected that the hypothesis itself might 
advantageously bear scrutiny. Finally a fault-boundary of a 
mountain-block was accidentally discovered far away from the 
line where plain meets mountain so sharply as the strand-line of the 
ocean. This fault was more than five miles from the mountain 
base — out on the smooth, flat plains. With this clue I examined 
anew many of the Desert ranges and established beyond perad- 
venture the independence of the fault-lines and the lines of the 
so-called fault-scarps. Furthermore, it was discovered that the 
distance from the crest of the range to the major fault-line out on 
the plains was about the same as from the crest to the base of the 
back-slope. The ranges were therefore bilaterally symmetrical. 
They would hardly be so if the mountains had been recently 
reared and tilted fault-blocks. These mountains were surely not 
the immediate product of recent tilting. 
Incongruous relations between neighboring districts which are 
being loaded and unloaded appear especially well displayed in 
California. There Dr. F. L. Ransome shows that the Great 
Valley is floored with recent sediments having a thickness of 2,000 
feet, that are mainly derived from the adjoining mountains. On 
the one hand, the Coast Ranges are demonstrated to have been 
upraised before the formation of the valley and are consequently 
independent of its loading and subsidence. On the other hand, the 
Sierra Nevada proves to have begun its elevation about the same 
time, or shortly after the Coast Ranges. In the broad trough be¬ 
tween were then deposited the great thickness of shallow-water 
sediments. 
Criticism of W J McGee’s argument for isostatic equilibrium 
in the Gulf of Mexico also brings out facts that are not com¬ 
patible with the assumption of pari passu local sinking under load. 
Closely analyzed, isostasy is found to be essentially an hypothesis 
of mere adjustment instead of initial movement. 
The well-known fact in geophysics that with reference to 
27 Bull. Geol. Soc. America, Vol. XXI, p. 560, 1910. 
28 Bull. Geol. Dept., Univ. California, Vol. I, p. 371, 1896. 
29 Am. Jour. Sci., (3), Vol. XlyIV, p. 177, 1892. 
