90 
PACIFIC SCIENCE, Vol. 1, April, 1947 
Stream, 2.1 miles from Anahulu Bridge 
at Haleiwa, along Kamehameha Highway, 
toward Waimea Bay. Figure 8 was photo¬ 
graphed from this point. To the right is the 
old, wave-cut cliff. The cliff leads up to 
fields of sugar cane, which show up in a 
rather light shade. The cane fields are on the 
top of the downthrown block. Beyond the 
Fig. 8. Distant view of the eroded and subdued 
scarp of the Waimea, Oahu, fault, from Lauhulu 
Bridge, looking northeastward. 
cane fields (and, in the picture, above the 
cane fields) is the eroded and subdued scarp 
of the upthrown block, marked by the darker 
shade of the trees that grow on it. The pic¬ 
ture, of course, cannot show Waimea Valley, 
but it lies between the cane fields and the 
wooded slope. Valleys that are due solely to 
erosion will normally have ridges of the same 
height on both sides, but since the northeast 
side of Waimea Valley rises some 200 feet 
higher than the southwest side, the valley is 
not solely the product of stream erosion. 
DIRECTION OF MOVEMENT 
A fault scarp results from the vertical 
movement of the block of rock on one side 
of the fault relative to the block on the other 
side. If one block is actually stationary, the 
other may move either up or down; or it may 
be that both blocks move but that one moves 
farther than the other; or the two blocks may 
move in opposite directions. 
At most of the faults in the Hawaiian 
Islands the higher block seems to have re¬ 
mained relatively'stationary while the lower 
block moved downward, probably as a result 
of the removal of support from below. The 
infacing fault scarps at Kilauea, for example, 
are thought to have resulted from subsidence 
of the central block at times when the magma 
column has receded. The last event of this 
sort was in May, 1924, when the diameter 
of Halemaumau, the inner pit, was increased 
from about one third of a mile to about two 
thirds of a mile, by the engulfment of the 
central part, leaving a scarp of sheer cliffs 
several hundred feet high. A month earlier, 
subsidence along a fault at Kapoho near the 
east point of the island of Hawaii made a 
scarp 8 to 12 feet high, and the sea flooded 
a part of the block that dropped downward. 
Numerous other examples of presumed 
downward movement of fault blocks in 
Hawaii could be cited. 
It is the writer’s opinion, however, that at 
the Waimea, Oahu, fault the lower block re¬ 
mained relatively stationary while the higher 
block was actually raised, because this as¬ 
sumption appears to be called for by the two- 
cycle topography on the higher block. 
Two-cycle topography results when a re¬ 
gion that is fairly well advanced in the ero¬ 
sion cycle has its streams rejuvenated by 
having their gradients increased. This in¬ 
crease of gradient might be due to either 
(1) a lowering of sea level or (2) a raising 
of the land area. If the rejuvenation in ques¬ 
tion were due to a lowering of sea level, then 
similar rejuvenation and similar two-cycle 
topography should be found in many of the 
older parts of the Hawaiian Islands. In con¬ 
trast, if the rejuvenation were due to unique 
uplift of this particular bit of Oahu, other 
parts of the Hawaiian Islands would not be 
rejuvenated and would not develop two-cycle 
topography. Inasmuch as the writer knows 
of no other places with similar two-cycle 
topography, he concludes that uplift of the 
higher, or northeastern, block took place. 
The writer freely admits that he cannot 
show the mechanism by which the northeast- 
