Answer:
<h2>Sea Stack -</h2>Thousands or even millions of years, in fact. Coastal erosion or the slow wearing of rock by water and wind over very long periods of time causes a stack to form. All sea stacks start out as part of nearby rock formations. Millennia of wind and waves hit the rock and break it down.
<h2>Sea Cave - (one photo included for this only)</h2>Sea caves or littoral caves are formed primarily from erosion caused by waves. They can be formed along the ocean coast and lakeshores where water impacts bedrock. Most sea caves are formed along weaknesses in the rock, such as faults, fractures, or bedding/foliation planes and can occur in nearly every type of rock.
<h2>Sea Sand Dune -</h2>Coastal dunes form when wet sand is deposited along the coast and dries out and is blown along the beach. Dunes form where the beach is wide enough to allow for the accumulation of wind-blown sand, and where prevailing onshore winds tend to blow sand inland.
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