16 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Plate 1 A shows a part of the mountain front, where the triangular end 
of a large spur between two large valleys is divided by three small 
ravines into four small spurs with more or less distinct terminal facets. 
The small ravines open on the Bonneville beach; recent fault scarps 
interrupt the slope of the Bonneville shore deposits, but do not exhibit 
the forward-reaching rock platforms that should be visible if the spur- 
end facets had been cut by the Bonneville waves, without aid by 
faulting. The foreground plain is the surface of a large delta at 
the Provo level. The view along the mountain base given in my 
previous paper was taken from the apex of the highest of the facets 
here shown. 
It may be well to state that special attention is given to details of 
form, such as are here illustrated, and that relatively little attention is 
given to structure apart from its relation to form, because it is essen- 
tially upon morphological evidence that decision must be made as to 
the origin of the range by faulting or otherwise. If the range were 
described only with respect to the age of its strata, the attitude in which 
they stand, the internal folding and faulting that they have suffered, 
and if no details were given as to the relation of base line and mountain 
front to structure and sculpture, it would not be possible for a reader 
to judge for himself whether block-faulting has played any part in the 
origin of the range or not. In the solution of any problem of this kind, 
there is a certain group of features whose critical determination is 
essential, and there are various other groups of features whose determi- 
nation is more or less irrelevant. The selection of the various features 
that are essential to the solution of the problem under discussion can- 
not, I believe, be accomplished without a careful deductive consider- 
ation of the problem as a whole; and it is for that reason that the 
deductive side of the problem was presented in some detail in my previ- 
ous paper. Following the results then reached, I shall now again give 
special attention to matters of mountain form, especially to the details 
of form along the mountain base line, and to the relation of these de- 
tails to the structures of the mass there exhibited; while various mat- 
ters that would receive close attention in a conyentional geological 
description of the range are here passed over rapidly; not because 
they are altogether irrelevant, but because in the short time at the dis- 
posal of our party it seemed best to attend to matters that bore most 
directly upon the problem of block-faulting. 
On July 13 we went up one of the deeper valleys on the western face 
and reached a rounded knob on the eastern side of the range at an alti- 
tude of about 8,400 feet: the summits of the range lay a mile or two to 
