well you saw that spot at tring dan,pure chalk from 150mm down
funny thing with chalk is that it bulks up a lot as it comes out
when a 5 tonne digger has broken 15 paving slabs and annihalated a lawn,you scratch your head and think "was it worth it?"
FTR i have seen DDD digging and he is very careful,but digger drivers like him are few and far between and more importantly always booked up
LLL