392 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION. 
away toward the south. The above shows that the movement was not directly down the 
hill, but was more to the south. The formation is sandstones and shales, with considerable 
soft surface soil. 
The same slide was subsequently visited by Mr. F. E. Matthes, and the following 
descriptive note is by him. (See 
figs. 68 and 69.) 
The slip occurred east of a high ridge 
at the southern end of the Sobrante 
Hills. It covers the northeast half of 
an area whose terraced nature is in- 
dicative of a former landslide of much 
larger dimensions. The accompany- 
ing sketches show the general outlines, 
and a cross-section of the slide. It 
will be noticed that the slide does not 
extend all the way down the slope, its 
lower edges being fully 100 feet or 
more above the bottom of the gulch. 
The lower slopes were not materially 
changed, and but little débris fell into 
the stream-bed. 
A steep scarp has been produced 
east of the crest of the ridge. The 
downslip along this scarp does not 
exceed 50 feet, and decreases both to 
north and south. Along the north 
edge there has been a marked move- 
ment down and southward, the scarp 
there averaging 10 feet. Along the 
south side, on the other hand, the loos- 
ened mass had advanced over the old 

Scale in feet (approx.) surface, presenting a bulging and 
2 uf hh: Contour interval 10 feet (approx) : 
PL PP cracked frontal scarp some 6 feet 
Fira. 68.— Map of landslide caused by the earthquake east high. It appears from this that the 
of San Pablo. movement took place, not along the 
: line of greatest declivity, but in a 
direction somewhat more southward, as indicated by the arrow. The 2 hummocks probably 
existed before the slip occurred, but judging by their greatly cracked and rent surfaces, it 
seems likely that their height has been slightly increased. The main crack, which extends 
southward from the upper scarp, contin- 
ues along the hillside in irregular zig-zags 
for some 300 feet south of the slide. 
(See plate 1284, B.) 

Other earth-slumps referred to under 
the section on the Distribution of Inten- 
sity are shown in plates 125B and 129a, 
By.G.D, 


EARTH-FLOWS. my} 
Unchanged slope 

Mount Olivet Cemetery (A. C. Lawson). 
— Perhaps the best illustration of an Rat 
earth-flow caused by a sudden accession Fic. 69.— Section of landslide shown in fig. 68, along 
; * the line 4-d’. 
of water to the incoherent materials of a 
slope, in consequence of the earthquake shock, is that which occurred in the upper part of 
Mount Olivet Cemetery, near Colma, 9 miles south of San Francisco. The locality is at 
the base of the San Bruno scarp, and about 2.75 miles northeast of the San Andreas 

