"Mark Godden's Little Bit Of Cyberspace Mk.II"

Typical Portland Roach - Sample From Bowers Quarry

Roach is a very shelly (fossil rich) and often very open stone. Roach from the north of Portland contains the distinctive high turreted gastropod Aptyxiella Portlandica or "Portland Screw" some of which are clearly visible in the picture above. Roach is a highly durable stone ( the "Cobb" at Lyme Regis is made of Portland roach) and is also very attractive when cut parallel to its bed and polished, roach is being used in this way (face bedded) as part of the rebuilding work to the BBC's Broadcasting House in Central London. Interestingly, roach was a favoured building stone for 19th Century defensive structures (the Nothe Fort, Weymouth is an example) as trials conducted by the military at the time, revealed that unlike other more dense stones, due to its open texture, roach tended to absorb the impact of cannon balls rather than shatter.