Wa II of A nto n in us. 551 



height of the land to the sea must have been less than 

 at present. 



Again, the great Wall of Antoninus, erected as a 

 barrier against invasions by the northern barbarians of 

 the territory conquered by the Eomans, must have been 

 brought down close to the sea level at both ends. Its 

 eastern termination is recognised by most antiquaries 

 as having been placed near Carriden, where the great 

 Falkirk flats disappear along the shore. Its western ex- 

 tremity, not having the favourable foundation of a steep 

 rising ground, now stands a little way back from the sea- 

 margin of the Clyde. When it was built it was pro- 

 bably carried to the point where the chain of the 

 Kilpatrick Hills, descending abruptly into the water, 

 saved any further need for fortification. But owing to 

 a probable rise of the land, a level space of ground, 

 twenty or twenty-five feet above the sea, now lies 

 between high-water mark and the base of the hills, 

 and runs westward from the termination of the wall 

 for several miles as far as Dumbarton. Had this belt 

 of land existed then, there appears little reason to 

 doubt that the Romans would not have been slow to 

 take advantage of it, so as completely to prevent the 

 Caledonians from crossing the narrow parts of the river, 

 and drive them into the opener reaches of the estuary 

 below Dumbarton. 



While the position of marine shells in situ proves 

 the former presence of the sea at a height of 20 or 25 

 feet above its present level, along both sides of the 

 island, it is possible that in the case both of the Clyde 

 and Forth, the change of level within the human period 

 may be partly due to silting up, though it must always 

 be extremely difficult to draw a line between the results 

 of the two operations. 



