At the west end of MV it is rock.
Obama’s house is on salt marsh/pond. It is mostly sand around there. All of his utilities are BURIED. There are no electric lines running to the house in any pictures.
Plus they have an inground pool. Again, unless they blasted when they put it in originally. Which is unlikely.
Yes, there are areas of sand but I stand by my post. MV is not mostly sand. It is mostly rock that was pushed there by glaciers.