68 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION. 
ridge, and the fault-trace climbs the end of this, following a narrow groove or ascending 
sag. Here also are ponds. Farther on it passes to the east of the ridge crest and follows 
a side-hill sag similar to the one followed 2 miles farther south, except that it is on the 
eastern instead of the western face of the fault ridge. (Plates 8B and 9a.) The apparent 
vertical displacement is here in the opposite sense, the west side having apparently dropt, 
but the throw is small. 
Thence the trace descends obliquely to the canyon of Olema Creek 150 feet below. 
Where the creek makes a decided bend toward the west the trace crosses it twice, and 
then follows near its west bank for several miles. Not far from the second crossing it is 
subject to a series of offsets, giv- 
ing to the trace as a whole the 
(Point Reyes Sta. same echelon character com- 
X ao monly observed in the arrange- 
ment of its details. It is note- 
worthy that where these offsets 
occur the trace swerves some- 
what toward the right. and the 
new line begins at the left, so 
that the arrangement is essen- 
tially a magnification of the 
arrangement of cracks in what I 
have called the echelon phase 
of the fault-trace. There is this 
difference, however, that the ele- 
ments of the larger echelon make 
a comparatively small angle with 
the general course of the trace. 
At several points in this part of 
its course the trace follows steep 
slopes from which the timber 
has not been cleared. On these 
slopes, which face the northeast, 
its course sometimes coincides 
with that of a very narrow sag 
occupied by marshy ground. 
Elsewhere it crosses an upland 
to which a series of sags gives 
ial a ' gentle undulation and here it 
Fic. 16.— Map of fault-trace from Papermill Creek south- 
ward. Seale, 1: 62,500. touches or passes near a number 
of ponds. (Plate 43.) The route 
of the fault-trace in this region and thence north to Papermill Creek is shown by fig. 16, 
a compilation based on data from several sources, including a few original measurements. 
A mile south of the village of Olema the trace enters a sag which is followed continuously 
for nearly 3 miles. At first the sag is narrow and is attached to the northeast slope of a 
ridge, but approaching the Shafter place the ridge crest sinks and a broad sag replaces it 
in the line of trend. (Plate 42s.) In following the eastern edge of this sag from the Shafter 
place to Papermill Creek the fault-trace also’follows the western base of a line of hills. 
The hills are peculiar in that their western, or more strictly southwestern, base, being 
determined by faulting, is nearly straight (plate 428); while their northeastern base, 
modified by the erosive action of Olema Creek, is scalloped. In this region the ridge phase 
of the fault-trace dominates, being occasionally replaced by the trench phase. (See 

