Mole hill Construction

How is that some everyday events are rarely witnessed?
I have frequently been asked by people: "How do you manage to see so much wildlife?" My response to this question tends to be two-fold: Firstly, that I try to get out and about to observe as much as I can; and, secondly that I look about me a lot. Many people do not see things because they are constantly looking at little other than the ground before their feet, or are concerned with other matters, such as talking with those in their company. I try to keep my eyes open and particularly receptive to any movement.
This morning I glimpsed some movement about thirty paces from me. My brain suggested that what I had seen was a mouse or a vole running over a molehill. I moved closer to the said molehill in anticipation of seeing this small creature, particularly as the grass was short and the ground lay open. What I did see was the movement of the molehill. It was being constructed before my eyes, something which is an everyday event, yet, for me certainly, rarely observed.
Molehills, as I understand it, serve two purposes (except when the moles are breeding and a larger version can hold the breeding nest,) one is obvious: they need somewhere to place the earth they have excavated to create a tunnel. The hills also serve as a ventilation shaft, allowing fresh air into the tunnels.
I watched the activity of the mole for about ten minutes. It moved more earth onto the hill at the rate of about every thirty seconds. At no point did I see the mole. This leaves me with a question:
Does the mole push the earth up head first or tail first. In other words, does it push the earth ahead of it; or, does it reverse the earth back up the tunnel?