yes it was,although it's not that clear in the photo
there used to be quite a wide path where you could cut across the union from the A259 coming out at Northdown Road,it's still visable but looks overgrown
I have a vague memory of the sand pit. I seem to remember it was steep, or cliff-like, if this makes sense.
I sometimes walked from the valley up the path from the A259 to the union you describe on my way to Tideway.