506 STRATIGRAPHY OF THE BED-ROCK SERIES. 
Though in a certain general sense it may be said, perhaps, that the Sierra consists essentially of 
an axis of granite flanked by sedimentary rocks, yet there is another and a stricter sense in which 
this is not true. By far the greatest bodies of granitic rock which occur in the range are found, it 
is true, in its higher and central portions. But the granite is by no means confined to this portion 
of the range, nor does it seem to be confined to any two definite belts, one occupying the central 
portion, and the other the western foot-hills of the range. On the contrary, it occurs in broad, 
irregular patches, scattered over the western slope of the range, here and there, from base to 
sumunit. 
The stratigraphy of the metamorphic rocks of the Sierra is a puzzle to me. On the western 
slope their strike is almost universally northwest and southeast, and their dip almost as universally 
at very high angles towards the northeast, that is, towards the crest of the range. These rocks 
are locally disturbed, of course. Their strike sometimes varies considerably within short distances, 
and sometimes their dip is to the southwest of the vertical ; but these local disturbances are not 
so great but that the whole series of auriferous slates may be said to be conformable from the base 
of the range to the highest points at which they occur toward the summit. Yet the aggregate 
thickness of these strata is, in many parts of the range, so enormous as to make it hardly credible 
that they can constitute a single consecutive series, deposited between the earliest epoch to which 
any of the stratified rocks of the Sierra have been proven to belong, and the upheaval of the range 
in the Jurassic. 
But if these rocks be not a consecutive series, then how and by what means have they been 
folded in such perfectly parallel masses, presenting only their broken and eroded edges at the sur- 
face, and dipping at such universally high angles to the northeast? There is, indeed, no lack of 
possible causes and conceivable forces which might have produced such a result ; but I know of 
no positive proof that any particular force or set of forces is the one that has produced it, even 
if such be the fact at all. In fact, so far as my own knowledge is concerned, the whole question 
of the stratigraphy of the metamorphic rocks of the Sierra is yet a mystery. One fact which adds 
yet more difficulty to the problem is the frequent absence of any noticeable amount of local dis- 
turbance in the immediate vicinity of heavy masses of granitic rock. This fact is so frequent that 
I know not how to account for it on the supposition that the granitic rocks are all eruptive ; and, 
taken in connection with the occasional distinctly bedded structure of the granite, and the oceur- 
rence in it —in some localities at least — of hornblendic nodules of lenticular form, with a general 
parallelism in the directions of their axial planes, it seems to me at least very suggestive of the 
question whether a portion at least of the Sierra granite may not be metamorphic in origin. In 
this connection I may allude once more to that characteristic Mount Whitney form which is 
repeated in so many of the culminating peaks of the range on the west of Owen’s Valley. There 
has surely been some special cause for the repetition of this same form so frequently there, nor can I 
readily believe that it has been exclusively the action of external forces. Whatever may be due 
to the sculpturing power of ice and snow, or to the character and direction of other erosive forces 
which have aided in carving the peaks, I cannot help thinking there is probably something in the 
structure or texture of the rock itself which has contributed in no small degree to the production 
of this peculiar form. 
With reference to the greater morphological features in the structure of the Sierra at large, I 
believe that these, except in so far as they have been subsequently modified by volcanic and 
erosive action, existed from the beginning, or at least from a very early period in the history of the 
range ; that is to say, I believe that the greater and loftier spurs which stretch here and there so 
far down the western slope of the range, and mark the dividing lines between the greater of the 
modern drainage basins, as, for example, the ridge between the South and Middle Forks of the 
American, and also the greater of the isolated ridges which, in places far down on the western 
slope, rise high above everything else around them, as, for example, the Calaveras County Bear 
Mountain ridge, are probably as old in their elevation as the crest itself, and were uplifted with it 
to heights above the adjacent regions. 
