The continual battle between land and sea is apparent here - along the northwest coast of America - where erosion is the predominant force.
Millions of years ago, this coastline would have looked very different.
Even though the land is tough basalt, the relentless attack of the sea has eroded it in spectacular ways.
Cliffs are formed when weathering weakens the top of the land and destructive waves attack the bottom of the rock face.
Weak points in the rock are affected most, and eventually form a hollow, called a wave-cut notch.
The overhanging rock collapses, and the rubble is carried out to sea, forming a wave-cut platform.
The whole process continues, causing the cliff to slowly - but continually - retreat.
But erosion also produces more unusual features.
Hollow caves can be carved out by the water and eventually break through, forming an arch.
The continual erosion keeps widening the arch until it can no longer support the land on top.
The arch collapses and leaves a headland on one side, and a tough outcrop of rock on the other - called a stack.
Whilst erosion constantly attacks our coastlines, deposition builds characteristic landforms.
When constructive waves wash on to the shore, they dump material carried in the water, like sand, pebbles and rocks.
This builds up beaches.
Whether a beach is soft and sandy or hard and pebbly depends on both the wave energy and the local geology.
A narrow, extended stretch of beach that projects out to sea is called a spit.
These are formed by deposition as well, but wind conditions also have a part to play.
Where the prevailing wind blows at an angle to the coast, it causes longshore drift.
Material is moved along the coast at an angle.
Over time, the wind and waves affect the end of the spit, causing it to curve to create a hook end.
This creates a sheltered area protected from incoming waves.
Silt is deposited, and mud flats or salt marshes can form.
Erosion and deposition have created the world's beautiful and dynamic coastline, and continue to affect these ever-changing landscapes.