I am putting a raised flower bed along an existing dry stone wall in my
front garden. It will be made from 4 courses of 75mm high dressed
walling (sand) stone. It will be 4.5 m long with a 0.5m return on either
end.

Top view looks like:


================================================== ===============
Top of Existing Drystone
================================================== ===============

#
Flower Bed Here #
#
################################################## #######
#
#
#

Does anyone have any info on what depth of footing would be suitable for
this wall? Ground is very solid and full of rocks (live near a disused
quarry road). Most of existing soil will be re-used to fill bed.

Any other tips (drainage etc) would be appreciated too...

Thanks in adv,

Alex.