JOHNSON: GRAND CANON DISTRICT. 155 
cane Ledge. This butte, known as Sugar Loaf Mesa, is seen in the 
distance in plate 22 (fig. 1). According to Huntington and Goldthwait 
('04, p. 224-225), the continuation of the lava cap is found at the base 
of the Ledge, on the downthrow side of the fault, covering different 
(lower) beds from those under the cap in the butte. It is clear from 
this that there must have been a displacement before the lava flow, 
bringing different rocks opjiosite each other, followed by baselevelling 
to reduce the rocks on both sides to a uniform level, over which the 
lava was spread across the fault line; also a displacement after the 
lava flow, producing the present break of hundreds of feet between the 
two parts of the flow. These are the two movements along the fault 
line recognized by Huntington and Goldthwait. 
On the face of the limestone cliffs overlooking the downthrow side 
of the fault, and two to three hundred feet above the base of the cliffs, 
is a thin strip of lava (pi. 21, fig. 1) which adheres to the rugged cliff 
face along several miles of the fault, although removed by erosion in 
places. This lava strip is represented on the geological map by Hunt- 
ington and Goldthwait, but its significance is not discussed by them. 
It is probable that they regarded it as a fault splinter broken from 
the main lava cap when it was downfaulted, in which case it would 
have no special significance. 
The lava strip does not appear to represent a fault sjilinter, how- 
ever. Its contact with the limestone back of it is an irregular, igneous 
contact, produced by the flowing of the liquid lava against the face 
of the cliff ; and wherever a stream valley occurs in the limestone cliffs, 
the lava strip follows up the valley for some distance. There is no 
evidence of faulting between the lava and the face of the limestone 
cliffs. The lava strip was traced far enough south to see that it could 
have no possible relation to the cap of Sugar Loaf jNIesa. The exist- 
ence of any peculiar warping or splintering of the former lava cap to 
produce such a relation is thus excluded. The conditions are essen- 
tially as represented in the accompanying diagram (fig. E). 
As showTi by the figure, three faulting movements are necessary to 
bring about the conditions indicated in the field: (1) the ancient fault, 
bringing different rocks opposite each other, which were then pene- 
plained and covered by the lava flow aa', as demonstrated by Hunting- 
ton and Goldthwait; (2) a second fault dropping the rocks west of the 
fault down to the position indicated by the dotted lines. After con- 
siderable erosion of the fault cliffs, a volcano west (?) of the fault 
