Magnetic Spherules — PETTERSSON AND Frederiksson 
73 
TABLE 1 
CORE NO. 
DIAM. OF 
CORE, MM. 
LENGTH OF 
CORE IN 
METERS 
LATITUDE 
LONGITUDE 
DEPTH 
IN METERS 
NUMBER OF 
SAMPLES 
71 
46 
10.0 
S 7°38' 
w 
152°53' 
4990 
16 
90 
90 
5.2 
S 3°21' 
E 
174°12' 
4830 
49 
90 B 
26 
0.3 
S 3°21' 
E 
174°12 / 
4830 
1 
92 
90 
5.2 
S 1°20' 
E 
167°23' 
3960 
25 
133 
90 
3.3 
S 11°33' 
E 
91°26' 
5200 
18 
187 
46 
9-5 
N 33°59' 
E 
31°02' 
2500 
16 
17 
46 
N 43°28' 
E 
7°22' 
2030 
1* 
18 
46 
N 4l°29' 
E 
5°5T 
2680 
1* 
87 
46 
N 2°23' 
W 173°50 / 
5560 
1* 
89 
46 
S 2°48' 
W 178°57' 
5480 
1* 
* Separate sample from the surface. 
of 1:2. The average number of spherules per 
kg. for the whole core is about 300 (see the 
curve in Fig. 3). 
According to radium measurements, made 
by Kroll (1955), in the sediment where cores 
71 and 72 were taken, the rate of sedimenta- 
tion is taken to be between 1 and 2 mm. in 
1,000 years. 
core 72. This core was raised from the 
immediate vicinity of Core 71, where the 
sediment had the same character. Its upper- 
most 3 metres, out of a total length of 14 
metres, have been examined for spherules by 
Laevastu and Mellis (4). In Figure 4 the re- 
sults from their counts are reproduced from 
their original paper. In Figure 3 the number 
of spherules is set out for the same levels in 
which Core 71 has been investigated by us. 
The figures, however, have been reduced to 
50 per cent to be in conformity with our 
counts, since Laevastu and Mellis included 
spherules from diameters 10 /jl upwards in 
their counts, whereas our counts in Core 71 
are limited to diameters of from 30 n upwards. 
According to Laevastu and Mellis the spher- 
ules of less than 30 g, in diameter made up less 
than one half of the total number. 
core 90. This is a thick core, 90 mm. in 
diameter. Its total length is, therefore, very 
moderate, or only 5 metres. In its upper part 
the content of lime is low, less than 1 per cent. 
Below the 190 cm. level the content of car- 
bonates increases abruptly to about 30 per 
cent, rising still further down to more than 
80 per cent. The number of spherules varies 
greatly. From about 3,300 per kg. near the 
surface, a maximum of 5,000 is reached be- 
tween 80 and 90 cm. Below the 110 cm. level 
the number of spherules per kg. of salt- and 
carbonate-free sediment is less than 1,000 
(minimum 140), with the exception of a sec- 
ondary maximum of 1,300 in a depth of about 
280 cm. 
Two parallel series of samples from this 
core were extracted. The results obtained from 
the first five samples in the first series (see 
full drawn curve in Fig. 5) were much lower 
than those from the second series. This is 
probably due to the fact that the technique 
of extraction had not been fully developed 
at that time, so that a certain number of the 
spherules may have become crushed in the 
extractor and thus escaped the counting. 
In certain samples it proved very difficult 
to distinguish between different types of 
spherules, of which the black shiny ones were 
primarily counted. This difficulty may explain 
the strong variations found by control counts 
from identical levels, especially as regards the 
sample between 63 and 80 cm. In the diagram 
in Figure 5 these variations are indicated by 
horizontal lines, uniting the highest and the 
lowest values found at the level in question. 
core 90 B. This was a narrow "pilot core" 
taken from the same vicinity as Core 90. The 
amounts of spherules in the lime-free portions 
in the uppermost 4-12 cm. and 0-6.5 cm. of 
Cores 90 B and 90 respectively were found to 
