Geoscience Reference
In-Depth Information
the chalk, referred to as 'clunch' are more suitable for
building (Clarke, 2004). Figure
59
shows 'Totternhoe
Stone', a clunch variety that is durable enough for use in
external walling. Figure
60
shows the slightly finer
grained 'Cambridgeshire Clunch', which is more widely
used for intricately carved, internal decorative stone
work and vaulting.
Many popular building limestones are produced in
Europe. Figure
61
shows 'Anstrude Stone' (Bathonian,
Jurassic), a buff-coloured oolitic limestone (oobiosparite)
from France, which also contains crinoid debris and has
calcite cement. Figuire
62
shows 'Buxy Stone' (Bajocian,
Jurassic), a beige/yellowish-red/grey compact crinoidal
59
60
59
'Totternhoe Clunch' (Bedfordshire, England)
limestone (packed biomicrite) consisting of shell
fragments (pink) cemented by microcrystalline calcite
(brown) with minor proportions of collophane fragments
(black) and traces of glauconite (green); XPT, ×150.
60
'Cambridgeshire Clunch' (Cambridgeshire,
England) limestone (packed biomicrite) consisting of
shell fragments (pink) cemented by microcrystalline
calcite (brown) with traces of quartz grains (grey),
collophane fragments (black), and glauconite (green);
XPT, ×300.
61
62
61
'Anstrude' limestone (France) consisting of ooliths
and bioclasts (including crinoids, orange/left) with a
cement of sparry calcite (white); PPT, ×25.
62
'Buxy Bayadere' limestone (France) consisting of
bioclasts (mainly crinoids) that are well cemented by
sparry calcite; XPT, ×35.
