76 
PACIFIC SCIENCE, Vol. XII, January, 1958 
Spherules per kg salt-and carbonate-free sediment. 
0 200 400 600 800 
Fig. 3. Number of spherules per kg. of dry sub 
stance from Core 71. 
the same levels were taken, the values varied 
considerably inter se. The average for the 
whole core is 190 spherules per kg. 
Regarding the rate of sedimentation in this 
core very little is known. O. Mellis (1954), 
from a study of the volcanic ash horizons 
present in cores from the eastern Mediterra- 
nean, has identified a layer of volcanic ash in 
Core 187, situated at a depth of 40 cm. below 
the top of the core. This layer probably owes 
its origin to the catastrophic outbreak of the 
island volcano Santorin, which occurred some 
time between 1800 and 1500 B.C., i.e., about 
3,700 years ago. This assumption would make 
the rate of sedimentation in the upper layers 
of the core about 10 cm. in 1,000 years, leav- 
ing aside possible disturbances in the sedi- 
mentation due to slumping, etc. 
Regarding the two maxima found in Core 
187, it should be noted that the spherules 
they contain were especially difficult to iden- 
tify, resembling some of the samples in Core 
90. The values given here must, therefore, be 
stated with due reserve and have only been 
indicated in the curve in Figure 8. Neverthe- 
less there is little doubt that the maxima are 
real, even though the numerical finds are 
somewhat uncertain. Attempts to find such 
maxima in other cores from the vicinity are 
at present being undertaken. 
Considering the abrupt decrease in the 
number of spherules on both sides of the 
principal maximum, one is tempted to assume 
that at the time when the maximum occurred 
one or several meteoritic showers fell upon 
the eastern Mediterranean. An alternative ex- 
planation, that at the time when the maximum 
occurred there can have occurred an abnor- 
mally low rate of sedimentation, appears less 
probable. 
It would be most interesting to investigate 
other cores, preferably of larger diameter, 
taken in the vicinity of Core 187. 
MAGNETIC SPHERULES FROM THE 
ATMOSPHERE 
The problem of finding by direct observa- 
tion the amount of magnetic particles settling 
SPHERULES/ kg. DRY SUBSTANCE 
0 500 1000 1500 2000 
Fig. 4. Number of spherules per kg. of salt- and 
carbonate-free sediment from Cores 71 and 72. 
