818 
MR J. M. WORDIE ON THE NATURAL HISTORY OF PACK ICE 
being the result of two winters’ freezing. Both these winters may have been spent 
as drifting pack-ice, or for the first of them the ice may have been held fast in some 
sheltered bay. 
Summary Table of Rate of Growth. 
Locality. 
Date. 
Thickness. 
1915. 
inches. 
Centimetres. 
D 
14th February 
0 
0 
16th February 
6 
15-25 
3rd March 
12 
30-5 
13 th March 
15 
38-1 
6th April 
21 
53-4 
1st June 
375 
95-25 
6th July 
40-35 
102-5 
F 
6th February 
9th August 
0 
Small amount 
7th September 
1 36 | ° fsn0W ' 
13 th October 
57 
1451 C0VeriD K 
L 
5th October 
1301 Same floe as 
10th October 
131 1 F, but deeper 
21st October 
14 1 J snow-covering. 
Certain floes, however, whose thickness was due entirely to freezing, exceeded 
5 feet. Some of these were measured while still afloat, others immediately after being 
hummocked. A selection is given below of those of most interest, and from some of 
which important conclusions were drawn. 
Table of exceptionally Thick Floes due to Freezing. 
Date of Observation. 
Thickness. 
Remarks. 
8th August 1915 
145 cm. 
Pressure ridge beside ship. The ice in which 
the ship was beset in January-February 
1915. (80 cm. formed in 1914; 65 cm. 
formed in 1915, as proved by diatom layer.) 
5th and 12th September 
1915 
7i ft. 
Part of a hummock. Diatoms were present 
only in the lowest part ; presumed, therefore, 
to have formed almost entirely in 1914, and 
to have grown a few inches only in 1915. 
8th December 1915 
9-10 ft. 
A slab in a hummock, not very far distant 
from the last locality. 
31st December 1915 
7 ft. 
“ Ocean Camp ” floe. 
7 th February 1916 
6 ft. 
“ Patience Camp ” floe. 
19 th March 1916 
6 ft. (approx.) 
Portion of hummock nearly 25 ft. in height. 
Upper part made up of 2-3 ft. of “ spotted 
ice” with diatoms at base, lower of 1-3 ft. 
of “ fibrous ice ” with current summer’s 
diatoms at base. 
30th March 1916 
8 ft. 4 in. 
“ Patience Camp ” floe. Less snow presumably 
than where measured on 7th February. 
Vertical lines pronounced from the very top 
downwards, i.e. all fibrous ice. 
