The Severn is the longest river in the UK. It carries a large volume of water and has a wide tidal range, and one consequence of this is that the water at the tidal end of the river is made brown with mud stirred up by the turbulent currents.

These photos were taken along the lower reaches of the river, starting and ending with the two motorway bridges - the first opened in 1966, and the second in 1996.

The first Severn Bridge replaced the Beachley-Aust car ferry, which crossed the river at the same point, and this is what remains of the Aust terminal. A well-known photograph of Bob Dylan was taken near this spot in 1966, shortly before the ferry closed down.

Alongside the bridge is the Severn Powerline crossing, built in the 1950s, the longest overhead power line span in the UK at just over a mile.

Just up the river from the first Severn Bridge is the entrance to Sharpness Dock and the Sharpness Canal, which bypasses an unnavigable stretch of the Severn allowing shipping to reach Gloucester Dock. The Sharpness Canal is still used by commercial and leisure vessels.

At its southern end, the canal runs very close to the bank of the Severn. For many years old hulks have been beached and sunk on the river bank, where they help to prevent erosion. Most of the hulks are wood, but there are also the remains of concrete barges built during WW2 when steel was scarce.

The Beachley-Aust service was not the only ferry crossing - people also crossed the Severn from a point near the Black Rock lighthouse on the Welsh side to New Passage, near Severn Beach, in England. The wharf is still there, with its mooring ring worn by decades of use. The turbulent currents show where sandbanks lie just below the surface.

The second motorway crossing opened in 1996, from Severn Beach on the English side to Caldicot in Wales. The motorway bridges aren't the only crossings over this part of the river - almost underneath this bridge is the Severn railway tunnel.