Perhaps it was associated with the colliery that once stood here. When, as boys, my friends and I first walked to this little valley we discovered a derelict water-filled pit shaft surrounded by a fence. We threw a stone in and timed how long it took to reach the water. I seem to remember that it took, by our counting, at least two seconds, which would have made it a hundred feet deep!
From down here by the brook, Thornhill Edge is a prominent feature. A sketch map by Barbara Nuttall of medieval Thornhill shows Deadman's Lane climbing the fault scarp of the Edge.