I 
Fault at Waimea, Oahu 
Harold S. Palmer 1 
INTRODUCTION 
This paper is planned to show that a fault 
cuts the shore line of the island of Oahu at 
Waimea Bay, 7 miles southwest of the north 
point of the island. It is thought that this 
is the first time that a fault of appreciable 
offset has been unequivocally detected in the 
island of Oahu. 
Stearns (1935: 82, 173, 414) makes little 
mention of faults in his comprehensive re¬ 
port on the geology of Oahu. He thinks that 
a certain cliff in the Waianae Range, buried 
by later lava flows, may have been caused by 
faulting, although he says that the cliff may 
well have some other origin. He also de¬ 
scribes several minor faults. 
In regions underlain by extensive, uniform 
beds of rock, faulting is often manifested by 
an offsetting of readily identifiable layers 
along the surface of fracture. In many places 
the offsets may be seen on valley sides or in 
artificial excavations. This type of evidence 
of faulting is not applicable in Hawaii be¬ 
cause the individual lava flows vary so much 
in texture and in thickness that they are not 
readily identifiable. Continuous tracing of 
an individual flow is of little use because 
most flows are rather narrow, and not ex¬ 
tensive. 
In the uneroded, younger parts of the 
Hawaiian Islands, bold cliffs have been made 
by faulting. The block of rock on one side 
of the fault has been dropped, so that a bold 
cliff leads up from the edge of the dropped 
block to the edge of the stationary or rela¬ 
tively raised block. The infacing cliffs at 
1 Department of Geology, University of Hawaii. 
Manuscript received October 22, 1946. 
Kilauea and the cliffs that cut the shore line 
of the island of Hawaii at South Point and 
at Kealakekua Bay are almost certainly such 
fault cliffs. 
In the strongly weathered and eroded older 
parts of the Hawaiian Islands, any fault 
cliffs that may have existed formerly have 
become much subdued and are no longer 
conspicuous features of the landscape. The 
existence of such faults can be demonstrated 
only by less direct evidence. 
In the present paper the hypothesis is 
adopted that a fault extends inland from 
Waimea Bay in a direction a little south of 
east, and that the block on the north side has 
been raised relative to the block on the south 
side. Several consequences of this hypothesis 
are deduced, and the consequences are found 
to agree with features actually existing in this 
part of Oahu. 
I am greatly indebted to Dr. Chester K. 
Wentworth and to Dr. A. Grove Day for 
carefully reading the manuscript and giving 
me valuable suggestions for its improvement. 
OFFSETTING OF THE SHORE LINE 
Where a coastal region has a seaward slop¬ 
ing surface, and is cut by a fault at a large 
angle to the shore line, the block that is rela¬ 
tively raised will have its shore line shifted 
seaward. This kind of offsetting is diagram- 
matically illustrated in Figure 1, in which 
the upper sketch represents a dome-shaped 
island, such as the Hawaiian volcanoes build. 
The lower sketch shows a similar dome cut 
by a fault perpendicular to the shore line. 
The block on the left is the up thrown side 
and has its shore line displaced seaward from 
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