80 
Another still greater uncertainty enters into 
the calculation owing to the imperfectly 
known rate of sedimentation. Here one has 
to use approximate values involving possible 
errors by the factor of 2 to 5, in some cases 
even more. 
The following values worked out at the 
present stage of our investigation must be 
given, therefore, with due reservation. Com- 
pared to earlier figures given by other in- 
vestigators our estimates are very moderate 
but are necessarily subject to an revision when 
more extensive investigations now pending 
have been carried out. 
In general one gains the impression from 
these tables that the meteor frequency has 
been considerably above the average in recent 
times, as is also indicated in most of the 
frequency diagrams. However, we must em- 
phasize the great difficulties inherent in the 
method of sampling. First, the surface layer 
may be missing, a layer which may quite well 
represent a sedimentation time of tens of 
thousands of years. Further, owing to differ- 
ent rates of sedimentation, a whole core like 
No. 187 probably represents a sedimentation 
time of less than 100,000 years, which cor- 
responds only to a couple of cm. in Core 71. 
Hence, it is desirable to investigate a series 
of cores from different localities in order to 
arrive at really dependable values for the 
accruement of spherules and by this means to 
interrelate the results obtained from different 
cores. 
PACIFIC SCIENCE, Vol. XII, January, 1958 
Apart from the results given in the dia- 
grams and in Table 3 we also have values 
from four other samples, two from the upper 
layers of two western Mediterranean (Cores 
17 and 18), and two from the western Pacific 
Ocean (Cores 87 and 89). From Cores 17 and 
18 the number of spherules per kg. lime- and 
salt-free sediment is 260 and 150 respectively, j 
Assuming that the frequency of spherules is 
inversely proportional to the rate of sedimen- 
tation at a certain time we can, by comparison 
with Core 187 from the eastern Mediterra- 
nean, form an estimate of the rate of sedimen- 
tation in the western Mediterranean. We thus 
find a sedimentation rate of about 80 mm. in 
1,000 years for Core 17 and a rate of 130 mm. 
in 1,000 years for Core 18, which are both 
quite reasonable figures. For Cores 87 and 89 
the numbers of spherules were 1,725 and 
1,165 respectively, and through a comparison 
with Cores 90 and 90 B we obtain a sedimen- 
tation rate of 6 and 8 mm. respectively in 
1,000 years. These figures are three to four 
times higher than those found by Kroll (1955) 
from radium measurements. However, we do 
not know how far the uppermost samples in 
different cores represent the same span of 
time. 
SUMMARY 
The present paper gives the results from a 
study of the number of "cosmic spherules" 
present in sediment cores obtained from 
great depths in different parts of the ocean. 
TABLE 3 
ANNUAL ACCRUEMENT OF 
BLACK SPHERULES 
Rate of 
Number of 
Number 
Weight 
Total 
Core 
Depth 
sedimentation 
CaCOs 
Span of time 
diam. > 30 
(> 30 M ) 
in tons 
weight 
No. 
in cm. 
mm/1000 y 
per cent 
in years 
per kg. 
(10“) 
(< 60 ju) 
in tons 
187 
0-39 
100 
35 
0?- 3,700 
190 
4.7 
790 
2,400 
90 
0-6.5 
3 
1 
0?-20,000 
3,350 
1.6 
265 
800 
90 B 
4-12 
6 
56 
7,000-20,000 
3,350 
1.6 
270 
800 
92 
64-81* 
50 
76 
13,000-16,000 
220 
1.1 
190 
600 
133 
3-18 
10 
15 
3,000-18,000 
700 
1.0 
160 
500 
71 
0-26 
1.5 
1 
0P-200, 000 
1,400 
0.31 
60 
175 
72 
0-300 
— 
— 
— 
— 
— 
. 
125 f 
* Section 0-64 cm. lost in transport, 
t According to Laevastu and Mellis. 
