Dry Sanford Pit
I found this nature reserve on the Berks, Bucks and Oxon Wildlife Trust page. It is well worth a visit. It is easy to get to, there's lots of parking and there's plenty of space to wander around. I took my son and we were there for over an hour - and it was just a reccy for a warmer day.
There are a couple of entrances to the reserve. One is on Lashford Lane - you would need to park on the road - and there is another a bit further down the road, it is well signposted with a big car park.
Someone had rudely left a big dog poo under this sign. Perhaps it belonged to a fox with a sense of irony.
Signs of wildlife...
There are fascinating explanation of the geology of the pit.