The short section of hurdle trackway had eroded out of the marine clay on the Swansea foreshore
A Bronze Age road has been found below Swansea's shifting foreshore.
The short section of track was discovered by a metal detector enthusiast and archaeologists have now dated it to around 4,000 years ago.
Woven from narrow branches of oak and alder the structure was covered in a thin layer of brushwood to provide a level walking-surface.
It was found in March when it was uncovered by storms but has since disappeared back under the marine clay.
Brian Price, a member of the Swansea Metal Detecting Club, reported the discovery opposite the Brynmill area to the Glamorgan-Gwent Archaeological Trust.
A sample was sent to the Beta Analytic Radiocarbon Laboratory in Florida for dating and was found to be from the early Bronze Age - sometime between 2140 and 1930BC.
The track was woven from narrow branches of oak and alder
Andrew Sherman, assistant project officer, said: "During the early Bronze Age the climate was drier and warmer than today and the sea level was significantly lower.
"The trackway was therefore probably built through a wet, marshy environment.
"Because it has been eroded by the tide it is impossible to tell whether the entire trackway was composed of hurdles, or whether occasional hurdles were laid to cross particularly wet patches of ground."
The trust said there was very little evidence of Early Bronze Age settlements in the area with lots of funeral and ritual sites such as barrows, cairns and standing stones, but no habitation structures.
"The explanation for this may simply lie in the nature of a nomadic existence, which militates against the construction of substantial dwellings," added Mr Sherman.