How do subsurface features effect surface features with regards to coastal geology?

Answer 1

one surface feature would be that water (ocean) which is a big contributor to land erosion. Another would be tectonic activity beneath the surface (especially if it is near a plate boundary ie. convergent or subduction boundary, which could cause volcanic activity. Volcanic activity can increase land and further the coast line ie. Hawaii. These are some features from subsurface geologic coastal changes that occur.