In article ,
JennyC wrote:


I don't really know the Chilterns.....And I must admit that I don't know the
difference between chalk and limestone. Actually I didn't know they were
'related' !!
Nick ????

Why me? :-)

The answer is that all were formed from the shells of diatoms,
shellfish etc. If it was merely deposited and the water driven
it became chalk. Exposed to heat and pressure, it became limestone.
Exposed to more, it became marble. Chalk is a sedimentary 'rock';
the others are metamorphic rocks.

From a gardener's viewpoint, the only useful difference is between
Dolomitic limestone, which contains a high proportion of magnesium
and ordinary limestone, which is almost entirely calcium carbonate.
The former is much less hostile to calcifuge plants.

In practice, the answer is shovel on plenty of shit, compost etc.
and don't bother with the real lime haters. Otherwise, most things
will grow. The downs are not exactly barren :-)


Regards,
Nick Maclaren.