An exceptionally smooth formation due to perfect weather conditions. The
wall-like formation of these tidal waves (see next page also) will be
noticed. The reason for this is that the downward current in the river
heads the sea-water back, and thus helps to exaggerate the advancing
slope of the wave. The exceptional spring tides are caused by the
combined operation of the moon and the sun, as is explained in the
text.]
[Illustration: _Photo: G. Brocklehurst._