Portland Stone
The limestone formed in a shallow sea rather like the Bahamas today near
the end of the Jurassic Period, about 135 million years ago. The rock is composed
from countless minute structures called ooliths and these formed around grains of
sand or shell fragments that were rolled around on the shallow sea floor,
gathering layer after layer of limestone. The rock has an even structure rather like
cod roe and it can therefore be cut or sculpted in any direction.
This feature, coupled with hardness, colour and durability, gives the limestone its quality
as a memorial stone. The best beds lie at the top of the Portland Limestone series
and are known as the Base Bed, Whit Bed and Roach Stone. The rocks become
increasingly shelly towards the top and their character
is suitable for different applications.