This takes me back a couple of years to a discursion (c/f discussion) we had upon geological terms:

http://wordsmith.org/board/showflat.pl?Cat=&Board=miscellany&Number=16224&page=&view=&sb=&vc=1

[Sorry if I just wide screened you - could never work out that 'make a shorter link' thingie]

One often hears of 'kettle and karst' terrains. YCLIU.

stales