Deep Cores of Oahu — S tearns and Chamberlain 
155 
two holes have been drilled into the basaltic 
basement of Midway Atoll. The same equip- 
ment used on the Oahu holes was used there. 
These holes penetrated deeply weathered basalt 
overlain by basaltic conglomerates, marine sedi- 
ments, and coral reefs similar to those above the 
Oahu holes, indicating a long erosional and 
weathering period in the history of ancient 
Midway volcanoes prior to submergence 
(Stearns, 1966). 
3. A proposal exists to drill a hole in the 
Kailua area of eastern Oahu to study the 
mantle-like material that appears to be close 
to the surface in that area. The hole will be 
drilled on land and probably will be over 6,000 
ft deep. 
All of the above studies are related in that 
geologic data in the form of complete lithologic 
sections of the crust are to be obtained by 
deep drilling. These data will allow a more 
complete understanding of the geologic history 
of the Central Pacific Basin and a more exact 
knowledge of the tectonic and eustatic history 
of the Hawaiian Archipelago. 
The two holes (Ewa Nos. 1 and 2) recently 
WELL 273B 
Depth Log Remarks 
EWA I 
Depth Log Remarks 
WELL 164 
Depth Log Remarks 
WELL 162 
Depth Log Remarks 
0 — Mean Sea Level — 0 
-200 
Porous Reef Limestone 
Brown Stratified Silt 
-100 -B-H? Porous Reef Limestone 
Brown Mud 
Porous Reef Limestone 
Bedded Beach Rock 
Brown Lagoonal Mud 
Reef Limestone 
Brown Lagoonal Mud 
Reef Limestone 
g||{/-Gravel (1% Basaltic) 
u— Brown Limy Soil 
ptgjT'Gray Basaltic Sand 
400 -|§Sr| Brown Mud and Sand • 
pi I [Recrvstallized Limestone 
Sj ppnd Brown Mud 
§S— Lignite 
■ 200 \ 
113 Brown Clay 
' 300 S 
i 
-400HH 
Bf 
■500® 
H 
Reef Limestone 
ggf Limy Brown Mud 
_gOQ.|g|j- White Mud and Coral 
Lignite and DarkGreen Mud 
|||f s Black Basaltic Sand 
-700®| -700 i 
Coral 
Clay 
Coral 
Clay 
Coral 
Coral 
Clay 
White Clay 
-600 
ess Clay 
Hg I White Mud Alternating with 
c3[ Hard Reef Limestone 
-800 
I Hard Bosolt 
Weathered 
Hard Basalt 
Weathered 
Hard Basalt 
-300- 
-400 1 
-6p0 j 
-700 J 
Clay 
Coral 
Coral 
Clay 
Coral 
Clay 
Coral 
Clay 
Coral 
Clay 
Coral 
Weathered Basalt 
Hard Basalt 
_ qnn Jiil Dark Gray-Black 
yUU |4lf Calcareous Mud 
|gj j>lndurated Basaltic Sand 
Tan-Gray Limy Mud and Sand 
RSf Indurated Brown Basaltic Sand 
UNCONFORMITY— fSSf-Cobble-Pebble Conglomerate 
f.’f.'jfea.Soil 
nnnl- fc\Hard Basalt 
- 1 100 ■“ xlinker 
LEGEND 
Reef Limestone 
The width of the log is 
directly proportional to 
the hardness of the rock. 
^~bana ana bur 
h^J"Gravel, Boulders 
|6jj Brown, Gray and White Muds 
® Son 
0 
Green and Black Mud 
-Lignite 
Fig. 3. East-west geologic section across Ewa Coastal Plain, Oahu. 
