Rocks and boulders have all kinds of different sizes in general. If the coast/beach area is all smooth and uniform small particles (ie sand) then it would be ea

Rocks and boulders have all kinds of different sizes in general. If the coast/beach area is all smooth and uniform small particles (ie sand) then it would be easy to measure as long as you use a ruler larger than ~10 grains of sand. If there are ranges of particles from 1cm (pebbles) to 10 cm (rocks) to 10 meters (boulders) to 100 meters (rock outcroppings) then the effect kicks in.