PHYSICAL FEATURES OF THE IRISH SEA, 5 
is probably an area of about 1,298 
square miles of over 50 fathoms 
in the Irish Sea. On the western 
side the sea-bottom rises com- 
paratively steeply from the deep 
channel to the Irish coast, but on 
the eastern side there is a great 
plateau between the Isle of Man 
and England (see Fig. 2). Water 
of over 30 fathoms in depth ex- 
tends in from the west both to 
the north and, especially, to the 
south of the Isle of Man, forming 
depressions in an otherwise shal- 
low area that are important 
spawning grounds for fishes. 
These separate the Isle of Man, 
by moderately deep water, from 
Scotland to the north, and from 
Anglesey to the south, leaving it 
united to the northern part of Lancashire by a broad area of shallow water, which is scarcely 
in any part deeper than 20 fathoms. If, then, the floor of the Irish Sea were to be raised by 
that amount, 20 fathoms, the Isle of Man would be united by continuous land with England, 
and would still be separated by a LANCASHIRE 
, IRELAND 'SLEg OF MAN 
wide and deep channel from Ire- castle 
Nehundum B 
land. The section shown in Fig. : 
3, Where, to save space, the COTE res 
vertical scale is much greater renters: 
than the horizontal, brings out 
clearly this contrast between the depths in the eastern and western parts of our area. 
The region in which most of our work, 
both in the way of zoological investigation 
and in taking fisheries statistics, has been 
done is the shallow water off the Lancashire 
and Cheshire coasts, extending as far as 
Anglesey in one direction, and the Isle of Man 
in another (see Fig. 4). This area has along 
its eastern and southern sandy shores a belt 
of shallow water which is probably quite 
exceptional in the amount of Shrimps (Cran- 
gon vulgaris), of immature food fishes (mostly 
Pleuronectide), and of Cockles (Cardtum 
edule) which it contains. The 10-fathom 
line is on the average about 10 miles from 
land, and the area of shallow water within 
that line is about 2,091 square miles, while 
from the ro-fathom to the 20-fathom line 
encloses an area of about 2,885 square miles, 
