The highest tides occur when the moon is new and full and lower tides occur between these phases. Tides are also affected by the shape of the coastline, and tend to be intensified where there is a funnel effect, as in the Bay of Fundy. In the Bay, the difference between low and high tides varies from 3 metres at the mouth to about 16 metres at Burntcoat Head, the greatest tidal range on Earth. Tidal fluctuations play an important role in molding the coastlines of the Maritime Provinces. They are generated by wind on the water surface, and their intensity varies according to stormy or calm weather.
Waves vary in direction and power according to the direction and strength of the wind.
As a wave approaches the shore, its lower part hits the beach first and is slowed by friction, but its upper part is driven forward by its own inertia as a breaker. The swash drives the pebbles and sand shorewards, the backwash carries them out to sea. When the swash is the stronger, the wave is constructive and helps to add material the shoreline. If constructive waves are at an angle to the shoreline, the beach material is moved in the general direction towards which the wind is blowing. A destructive wave is one with a stronger backwash, which erodes the beach.