Deep-Sea Expedition— PETTERSSON 
235 
illegible when we moved against head-winds 
or an adverse swell because of air bubbles inter¬ 
fering with the ultrasonic beam. Even with 
this limitation, which results largely from the 
shallow draught of the "Albatross,” the echo- 
graph was most useful for our coring operations. 
The bottom profile showed an astonishing rug¬ 
gedness even at great depths. Perfectly even 
surfaces extending over greater distances than 
a few nautical miles were rarely met in the open 
Atlantic. A curious rise or fall of the bottom 
profile by "steps,” 20 to 50 fathoms and often 
considerably more in height, suggestive of faults 
across our course is quite frequent in the 
records. Professor Weibull, who personally 
followed the cruise to Cristobal, found dis¬ 
tinct echoes from a "bottom below the bottom” 
corresponding to a thickness varying between 
300 and 2,500 meters, i.e., values comparable 
to those found in the Mediterranean from the 
"Skagerak” in 1946. 
IN THE PACIFIC 
From Balboa we steered toward the Gala¬ 
pagos group (see map), raising sediment cores 
and taking a few oceanographic series under 
way. In the Bight of Panama a few hauls in 
750 and 1,500 meters, respectively, were made 
with our large ring net 2 meters in diameter 
in which catches of weird-looking bathypelagic 
fishes and invertebrates were brought up. 
The cores taken here were greenish-gray 
and rich in organic remains. In one case there 
was a distinct smell of sulphuretted hydrogen 
from the lower parts of the core. Near the Gala¬ 
pagos the sediment was of a light greenish color, 
was rich in foraminiferal tests, and in one case 
zones of dark volcanic ash were found in the 
lower levels. 
Our purpose in stopping at the Galapagos 
was twofold. While the men aboard the ship 
investigated the cool upwelling water south of 
the islands, which is rich in plankton, and took 
sediment cores from the bottom there, five of us 
went ashore on uninhabited James Island where 
we spent five unforgettable days collecting 
plants for our great Swedish authority on the 
Pacific island flora, Professor Carl Skottsberg 
of Goteborg. 
From James Island the "Albatross” followed 
a course to the WNW which afforded means 
for a complete oceanographic section across the 
Equatorial Countercurrent, where the two lines 
of divergence (upwelling water) and the line 
of convergence (descending water) were quite 
distinct. The oxygen minimum in intermediate 
water layers was also very conspicuous. An 
almost total lack of oxygen, less than 0.02 cc. 
per liter, was found in a depth of 150 meters as 
far north as latitude 14° 13' N, longitude 120° 
25' W. Close to the 18th parallel north, the 
"Albatross” turned south, crossing the Equa¬ 
torial Current System a second time during 
which we repeated the observations by water 
sampling in different depths and raising cores 
from the sea bottom. The sediment was mainly 
of the red clay type, but near the equator cal¬ 
careous sediments appeared which were rich 
in Foraminifera. Curious signs of stratification 
were also manifest. A great impediment to our 
coring operations, even at great depths, was 
the frequent occurrence of hard bottom which 
the core samplers could not penetrate. In a 
couple of cases this led to partial or total loss 
of the corer. In two cases at least, fragments of 
basaltic rock caught in the bit of the core 
sampler proved the obstacle to have been a 
lava bed covered by a thin veneer of sediment. 
Similar difficulties occurred also near Nukuhiva 
in the Marquesas. A botanical excursion was 
made to the high Tovii Plateau of Nukuhiva 
where bore kernels were taken from one of 
the rare peat bogs known in the tropics for 
future analytical examination for pollen. Be¬ 
tween Nukuhiva and Tahiti, where we arrived 
on October 24, our crop of sediment cores was 
very meager because of the hard bottom. 
The sounding of sediment thickness by depth 
charges gave results different from those found 
previously in the open Atlantic Ocean, in the 
Mediterranean, and in the Caribbean Sea. Vir¬ 
tually no definite signs of reflecting layers 
situated at more than 200 meters below the 
