ROMAN CAUSEWAY OVER THE CLYDE
Why did the Antonine Wall end at Old Kilpatrick? Or should we say start here? There are several theories why, but here are some considerations.
- The fort at Old Kilpatrick was very substantial. The western end of a string of forts and fortlets. But it could have been further west at the natural outcrop subsequently occupied by Dunglass Castle. Or further east where the Clyde was narrower.
- Together with the Firth of Forth, the Clyde formed a natural isthmus or definitive line across the country and this could be used strategically.
- The Romans also built less substantial progress forts, mainly of earthen embankments within which they camped and quartered their horses. One of these is on the upper slopes of the hill diagonally oppositeto the south west of Old Kilpatrick. This is near Bishopton just south of Greenock Road where it passes the Convent of the Good Shepherd, and also south of the Old Greenock Road. Such basic forts formed more temporary bases as the troops moved across the landscaped, but their locations also made sense when seen as planned to interlink with other bases.
The answer appears to be that they considered this a suitable fording point. Consider though the practicalities of doing so with horses, possibly also with wagons. Mud. Mud. Mud!
The answer is to stabilise the mud with rocks and other materials sufficiently to walk or drive wagons across without sinking in. Perhaps this also had timber and vegetation strewn across it, but that would have been washed away with each heavy flow. Such a structure is called a causeway. It does not necessarily have to be above the water level, as here, but may be submerged for part of the route, as long as men and beasts can get across safely. For a short distance they could have swum across, the mud being more a problem than water.
A causeway appears to be located opposite that fortlet near Bishopton. Intiguingly, it does not aim at the Old Kilpatrick fort but near to the western edge of what was to become of the fuel depot quayside. A notable feature is Milton Island, a small round solid rise in the mud. Canmore makes no mention of it being of historical significance, but being in line with the causeway was probably part of the route. Perhaps subsequent fishermen added to its size and round shape. Or perhaps the Romans had a small fortlet or watch house here alongside their crossing point. (Not to be confused with the crannog). The island is recorded as 'Green Inch' on William Roy's map of 1747-55. By 1821 the island is recorded as Millton Island, lying just off shore from the village of that name. it certainly is still green, being covered with water grass at low tide. [Kids Kiddle]. 'Inch' is Scots deriving from the Gaelic 'Innis', an island.
We must be a little cautious in claiming this to be a Roman causeway as some other possibiities exist, such as local residents and fishermen building it. But it certainly appears to fit in with the Roman scenario and is considered to be of Roman construction.
Canmore does record the following observations :
The River Clyde at Dumbuck could be forded in Roman times at low tide, and a causeway 7.0 metres wide has been found running north from the Longhaugh Lodge-Old Bishopton track at NS 430 726. It curves through the river-dyke at NS 430 730 and passes as a recognisable mound to the beach. Beyond, it porceeds as a cobbled way on top of a gravelly mound some 11 metres wide leading to the Long Dyke and Longhaugh Light. It is continued as a low mound about 10 metres wide running across Milton Island, NS 425 737, to pass through a field gate just east of the railway bridge at NS 424 741. From there it runs as a low mound 11 metres wide to the main Dumbarton road at NS 423 743. On the south side of the river a possible extension of the causeway towards the Bishopton fort has been sectioned at NS 425 724. North of Dumbuck a road has been traced, with some remains of metalling, as far as NS 461 822. ("metalling" is a term that is less common now, but refers to the hardening of a surface for traffic.
Theories abound as to quite how far west the Romans got. With their major fort at Old Kilpatrick it is imagined that they explored across much of this area - as far as safety from the locals could ensure. Dumbarton Rock will certainly have been visited and some suspect that they even had a presence at Ardmore Point. What the location of this causeway suggests is that they actually occupied much of the area immediately to the west of Old Kilpatrick Fort, bringing in supplies here, possibly trading with locals and also grazing their horses. This is much more than just a stoney line across the mud.
CANMORE : https://canmore.org.uk/site/43350/river-clyde-dumbuck
KIDS KIDDLE ; https://kids.kiddle.co/Milton_Island
