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PACIFIC SCIENCE, Vol. XXI, April 1967 
surface, the coral reef facies shifted landward, 
allowing the accumulation of a thick coralline 
limestone reef. 
9. The growth of this reef was followed by 
a progradation of the lagoonal facies during 
which time nearly 100 ft of brown lagoonal mud 
accumulated. The upper surface of this mud is 
capped by several feet of bedded beach rock, 
indicating a still stand at — 203 ft msl. 
10. Above the beach rock is another reef 
limestone section indicating a migration of 
coral facies landward again. After a short time 
this trend reversed itself, for at — 160 ft msl 
brown mud and soil occur, indicating a pro- 
gradation of the lagoonal facies. Both of the 
above two unconformities may correspond with 
the Penguin Bank stand of the sea. 
11. Above this level the coral reef facies 
advanced inland and dominated the remaining 
portion of the core except for one soil horizon 
at — 38 ft MSL that may correspond to the 
Waipio stand of the sea. 
12. The reef making up the present surface 
of the Ewa Plain appears to belong to the 
Waimanalo -|- 2 5 -ft stand of the sea, inasmuch 
as reef limestone can be traced from Ewa No. 1 
to Ewa No. 2 where it overlies lagoonal muds. 
The surface of this reef probably has been 
eroded by the sea as it retreated from the 
-j- 25-ft level to the last glacial low stand. 
CURRENT RESEARCH AND FUTURE PLANS 
It will be several years before the Ewa cores 
have been thoroughly examined. Even then the 
cores will continue to be used for comparison 
with cores obtained elsewhere. The interpreta- 
tion of results of the preliminary core examina- 
tion, especially of those sections dealing with 
the geologic history, doubtless will be modified 
as the research proceeds. The cores are stored 
at the Hawaii Institute of Geophysics, Univer- 
sity of Hawaii, Honolulu. 
The present plans for the examination of the 
Ewa cores include palaeontologic, mineralogic, 
and chemical analyses of selected samples along 
the core. Specifically the following types of 
studies are currently underway: 
1. Soil analyses. Chemical and mineralogic 
studies of samples from suspected soil hori- 
zons; climatic and other environmental inter- 
pretations of proven soils. 
2. Geochemical analyses. Absolute dating of 
various horizons within the cores by means of 
radioactive decay of certain elements. Methods 
used will include K-Ar, C 14 , and a new helium 
method. Paleo-temperature measurements will 
also be made. 
3. Palaeontologic analyses. Macro- and rnicro- 
palaeontologic studies of fauna and flora; de- 
terminations of geologic age by the use of these 
fauna and flora; paleoecologic studies. 
4. Sedimentologic analyses. Textural studies 
of the sediments and sedimentary rock; studies 
of the sedimentary environments. 
5. Mineralogic and petrologic analyses. 
Optical, chemical, and X-ray determinations of 
minerals and rocks, including analyses of the 
underlying basalts. 
The results of these analyses will give a 
partial answer to such questions as the tectonic 
history of the Hawaiian Archipelago and the 
nature and magnitude of the eustatic changes in 
sea level recorded in the Ewa cores. However, 
additional information will be necessary before 
the complete stratigraphic and paleoecologic 
history can be unravelled. Most of the sedi- 
ments in the Ewa cores indicate either a 
lagoonal or back reef environment. A very ex- 
tensive barrier reef undoubtedly lay to seaward 
of the present Ewa sites throughout most of the 
geologic period recorded in the cores. Without 
cores through this reef the stratigraphic inter- 
pretation of the present Ewa cores is handi- 
capped. Consequently, plans are underway for 
a research program to drill two more holes in 
the Ewa area, both offshore and in the area of 
the anticipated barrier reef. The first hole 
would be drilled in about 400 ft of water three 
miles off the beach along the 158th meridian. 
This deeper hole would be drilled over the 
1,800-ft shelf, possibly Miocene in age (Men- 
ard et al., 1962). Sediment thickness in this 
area is about 2,000 ft, based on seismic work. 
With the complete cores recovered from 
these two offshore holes it would be possible 
to trace completely the sedimentary facies 
changes from terrestrial to lagoonal to barrier 
reef both horizontally and vertically throughout 
the Pleistocene Epoch and possibly the bter 
Tertiary Period. 
