goksimaster - thanks

arran - for some reason it just jaggies the bottom edge when I add a smoothing modifier to the mesh. I'd not really noticed it so will probably delete the faces at the bottom and hope it goes away - I dont want people to think I'm modelling severed heads!

THX1138 - not sure, I'm probably going to look into doing a displacement map to generate that area and then see about converting it to a polygon mesh. The previous method worked out ok but took forever!