They may not be perpendicular to the current coast, but remember, long ago, the sea level was higher, and the coastline was different than it is today.
Understood, hence my caveat. BTW, could you help any with the Wando formation? Does it generally follow the present coastline? How far inland, etc? And, so I don't have to spend hours looking, again, how does it fit in with the age of the bays, etc?