A Wall made of Turf?

The western part of Hadrian’s Wall from the river Irthing to Bowness-on-Solway was first constructed as a turf rather than stone wall. The milecastles of the turf wall were built of turf and timber but the turrets were constructed in stone.  The wall seems to have been built of turf blocks cut from areas north and south of the Wall line and laid on a foundation of cobbles or turf blocks.  The wall was some six metres wide and the height has been estimated at around four metres with some form of wooden breastwork along the top. There was a ditch to the north with a narrow berm around two metres wide between the ditch and the wall.

In most cases the turf wall was removed when the replacement stone wall was built.  However, west of Birdoswald fort the stone wall was built on a different line and a stretch of the turf wall can still be seen a little to the south of the later stone wall.

Various explanations have been suggested by archaeologists as to why the western part of Hadrian’s Wall was first constructed in turf.  One theory is that wood and turf was more easily available in the west whilst convenient outcrops of stone were scarce.

Recently a Dutch archaeologist, Eric Graafstal, building on suggestions by other archaeologists over the years, has argued strongly that this western, turf wall was the very first part of Hadrian’s Wall to be built, constructed around 119 AD in response to a military threat from native tribes in the north west. Construction of turf and timber ramparts was standard practice for the Roman army. The Roman army on campaign constructed turf ramparts every night for protection. At the famous siege of the native hill fort of Alesia in Burgundy (France) Caesar’s troops constructed around 15 miles of turf and timber fortifications 4 metres high in about three weeks. The turf wall would have been a quick and practical response to a real or perceived threat in the north west.