Sec. iv] THE LAST WATCH-TOWERS OF THE LIMES, T. vt. c AND D 655
At the east foot of the tower the clay of the supporting terrace had crumbled away to some depth. Yet the tower still stood with but little damage even on that side, a striking proof that wind-erosion has had a very limited effect on this particular ground, which vegetation of some sort and marshy surface protected. The same fact was demonstrated by the terrace rising with easy slopes of soft clay, unlike the steep clay walls, undercut by erosion, of the terraces further north. I attribute the difference at T. vi. d to the fact that the marshy belt bordering this tower on the east and north prevented the prevailing east and north-east winds from attacking it with their most powerful weapon, the abrading, wind-driven sand. Unable to ascend to the top of the tower or to discover any trace of the quarters which are likely to have once adjoined it, I had to rest content with some small fragments of silk fabric picked up among the clay detritus at the foot as the only relic of ancient occupation.
Though the view to the south and west from T. vt. d was wide and open, I could sight nothing to suggest the existence of any other watch-stations. On a previous reconnaissance Surveyor Ram Singh, in accordance with the instructions given, had pushed from T. vi. d for over 9 miles straight to the west, and even further to the south-west, without discovering any other towers or remains. Consequently, I feel justified in concluding that this was the furthermost watch-post thrown out on the terminal flank of the Limes. From it the ground over which any possible attack might be made, or escape from ` within the barrier ' attempted, could be watched with ease for a great distance. The ` coast-line ' of the wide marshy basin is uniformly low towards the south, and shows none of those long narrow inlets which characterize the ` coast ' to the east and northeast. Apart from a small and low tongue close to the west of T. vi. d and overlooked from it, there are no projecting ridges or detached terraces for a considerable distance on this side. From the low clay cliffs of the ` coast-line ' the gravel ` Sai ' slopes up like a perfect glacis towards the rampart of huge dunes in the south, which has been previously mentioned. Right up to their foot, over twelve miles away, its absolutely bare surface was open to the view as I stood at the base of T. vt. d. Once more I felt impressed with that eye for topography which seems never to have failed the old Chinese designers of the Limes.
How serious an obstacle is presented on the south by the impassable nature of that great rampart of dunes was brought home to me when, towards the end of my explorations on this ground, I dispatched the Surveyor with most of the mounted men from Camp 172 to reconnoitre the ground on the south-east and, if possible, to push through to the route leading from the mountains to Nan-hu (Map No. 75. c, D. t). After a trying march for three days across the waterless waste he rejoined me, having been effectively baffled by the closely packed dunes which he encountered from about twenty-five miles' distance onwards, and which, after another ten miles or so, forced him to turn back and thus save his ponies from exhaustion. If ever there was a direct route followed from Nan-hu or the ' Yang barrier' to the stations on the south-western flank of the Limes, it must have lain across the gravel ` Sai' further north. But I have reason to doubt its existence.
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