Sunken lane

A sunken lane (also hollow way or holloway) is a road or track that is significantly lower than the land on either side, not formed by the (recent) engineering of a road cutting but possibly of much greater age.

Various mechanisms have been proposed for how holloways may have been formed, including erosion by water or traffic; the digging of embankments to assist with the herding of livestock; and the digging of double banks to mark the boundaries of estates. These mechanisms are all possible and could apply in different cases.

A variety of theories have been proposed for the origins of holloways. Different mechanisms may well apply in different cases.

Some sunken lanes are created incrementally by erosion, by water and traffic. Some are very ancient with evidence of Roman or Iron Age origins, but others such as the Deep Hill Ruts in the old Oregon Trail at Guernsey, Wyoming developed in the space of a decade or two.

Where ancient trackways have lapsed from use, the overgrown and shallow marks of hollow ways through forest may be the sole evidence of their former existence. On disused ridgeways in central Germany, the hollow ways often mark inclines.

The earth banks on either side, sometimes topped with hedges and trees, can give the impression of a tunnel enclosing the traveller. Because the roadway is restricted by the banks on either side, sunken lanes typically admit the passage of only one vehicle; that is, they are single track roads. Occasional passing places may be provided, but a meeting of vehicles in a sunken lane often requires one party to reverse to a suitable passing place. In Central Germany, "dual carriageways" have been observed with two trenches side by side where a trackway was in such heavy use that it had lanes dedicated for each direction.

Up to the present day, some writers have assumed that low banks were deliberately created with shovels as a means to hem in cattle, but there is no evidence for this, and in any case, banking only appears intermittently in certain types of soil. When metalled, sunken lanes are unlikely to erode any further down.

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Wikipedia