Well, I got a degree in the subject in 1980 but the old brain's a bit foggy these days...
To be frank Bean is the best qualified - doing her PhD in oceanography. I hear she's a bit busy at the moment so that's maybe why she hasn't chimed in to set us all straight.....
In her absence, I think Keiva and of troy make pretty good stand in oceanographers.... Both sorted out the matters of fetch and berms pretty well I thought. Fetch (the distance the prevailing wind travels over water) is one of the components that contributes to wave height - along with a few others that I've forgotten - but which include the depth of the water and the slope of the coast as I recall.
The sill depth is (I think) the depth to the continental shelf (help Bean!)
Noone seems to have mentioned cusps yet. These are the seaward pointing "horns" at each end of a berm - they point to where the rips are generally operating offshore. Both are features of a beach's winter profile - more wave activity in winter, steeper beaches, greater cusp and berm development.
Keiva was also correct to push for berm being a generic term, not necessarily for exclusive maritime use. Frinstance, there are berms in open pit mines. In this context however, their counterparts are not cusps but batters. The batters are the steep parts of the pit wall that link a series of horizontal batters.
stales
