236 THE RECENT BIRD TRACKS 
series of layers formed during the winter, none of these 
tracks occur. In the winter months the shores are en- 
cumbered with masses of ice and snow, and are quite de- 
serted. The floating ice scores and ploughs up the banks 
in exposed localities, and the regularity of the deposits 
must be very much broken during that time. The ice 
forming on the shores and floated off at high tide carries 
away an immense amount of shingle and loose material, 
often large boulders, and drops them over the bottom of 
the whole Basin, and one sees blocks of trap from Blom- 
idon lying on the flats about Horton and Cornwallis. This 
annual drift phenomena must leave its record in the 
boulders and coarse material distributed through the finer 
material laid down during the winter, while the summer 
layers would be entirely free from them. 
It will be readily seen that the mud deposits can 
only accumulate in the quieter parts of the bay, and 
that as we go from these to points where the tidal cur- 
rents increase in velocity, we shall pass from mud de- 
posits to those of sand and gravel, while the shores will 
vary in the character of their beaches according to the 
kind of rock exposed at the water’s edge. Thus under 
the red sandstone cliffs of Cornwallis and Blomidon, we 
have sand beaches in exposed localities, muddy shores 
where the waves are shut out, while trap-shingle is strewn 
along the shores of Blomidon. 
The Strait of Minas is very narrow, and one can read- 
ily imagine that the immense mass of water which twice 
a day is poured into the Basin, and twice a day drained 
off again, must cause tremendous currents setting through 
the strait, and that wherever these are felt, only the 
coarser deposits are to be looked for. 
These mud banks, these accumulations of sand, gravel, 
