I was out yesterday evening to try and get more photographs of the beavers near the house. I watched a beaver swimming across the water and close to the river bankedge, it dived under the water and did not appear again. I moved to the area where the beaver had disappeared and as I walked quietly towards the edge of the water I noticed some pieces of branch that the beaver had eaten, laying on the ground.
As I looked at them, the grass moved underneath them and I thought at first it was a vole moving in the grass, but as I watched a piece of branch was being pushed up through the grass from under ground. As I moved nearer, I heard the beaver run underground and go into water. In this picture I have pushed on of the branches into the hole (it was about 30cms deep).
Further along the river edge I found another burrow, but this time the beaver has been coming out of the burrow to access trees further away from the river edge
Here is a picture from inside the burrow
I have been searching on the internet but cannot find any reference to this behaviour.