88 
PACIFIC SCIENCE, Vol. 1, April, 1947 
stream courses, it does not concentrate stream 
flow to an appreciable extent. The situation 
at Waimea, Oahu, would seem to be midway 
between these two types, for our hypothesis 
supposes a fault only moderately oblique to 
the shore line. 
When Figure 5 was drawn, all the stream 
Fig. 5. Drainage map of the Waimea, Oahu, 
region, showing the concentration of perennial 
reaches of the streams near the fault. 
courses of the region were traced off from 
the topographic map. Some generalization 
resulted during the process of tracing. The 
intermittent reaches of the streams are shown 
as broken lines and the perennial reaches are 
shown as heavier, continuous lines. Except 
in the southeast corner it would be hard to 
find a point more than a third of a mile away 
from some stream course, which amounts to 
saying that the region has been rather in¬ 
tricately cut up into valleys and ridges. 
The perennial reaches of the streams, how¬ 
ever, show a decided concentration inasmuch 
as the three that are longest lie rather close to 
one another and rather close to the position 
of the suggested fault. The concentration of 
perennial courses is another item that agrees 
with the present hypothesis. 
PROFILE ACROSS WAIMEA 
The heavy, straight lines extending from 
northeast to southwest in Figures 2 and 5 
show the line along which the profile of 
Figure 6 was constructed. The profile was 
prepared from the preliminary sheets of the 
most recent topographic map of Oahu (U. S. 
Geol. Survey, n.d.), with a horizontal scale 
of a little over 3 inches to the mile. The 
vertical scale of Figure 6 is a little over four 
times as large as the horizontal scale. It will 
be seen that the high parts of the profile to 
the left (northeast) of Elehaha Stream are 
at altitudes around 800 feet, whereas those to 
the right (southwest) of Kaiwikoele Stream 
are about 200 feet lower. This difference 
would result from the vertical offsetting of 
the two blocks by the suggested fault. 
TWO-CYCLE TOPOGRAPHY ON THE 
UPTHROWN BLOCK 
Where the earth’s crust is stable, a stream 
will at first cut a rather narrow and deep 
valley, but as time goes on the valley becomes 
wider and more flaring because the rocks of 
the valley sides weather, become weak, and 
gradually slump or creep toward the stream. 
Thus a wider valley, with more gently slop¬ 
ing sides, will be made. 
Fig. 6. Topographic profile of the Waimea, Oahu, region, parallel to the shore line. 
