28o THE GATE OF THE ' GREAT WALL' CH.LXXV
support also from the height of the wall and from the dimensions of the towers lining it at distances varying apparently from one and a half to two miles. The tower of this old wall which I subsequently examined showed clay layers of identical thickness and the dimension of twenty-five totwenty-six feet square so familiar from the Limes of Tun-huang.
I had gathered enough evidence to convince me that the wall stretching away from here to north of Su-chou and Kan-chou was in reality but the continuation of the frontier defence line which I had traced through the Tunhuang desert and then again near An-hsi. But the hope of exactly testing its date here by excavations had quickly to be abandoned. Cultivation extended to the very foot of the old wall and even in places beyond it, and, what with the moisture of the soil and man's destructive vicinity, the chance of any datable records surviving along its line was scanty indeed. In another direction, too, I had to resign myself. The old wall stopped completely where it strikes the Chia-yü -kuan barrier, and of the stretch of about a mile which would be needed to take it on to the precipitous slopes of the Hao-shan-k'ou ridge, I was unable to trace any distinct remains.
Along that ridge itself, which forms a formidable
flanking defence for the great route west of Chia-yü-kuan, a wall was certainly needless. There was not sufficient time to try and fill the gap by a minute search of the barren stony glacis sloping up to the rugged spurs ; for the continued survey of the other line of wall running northward was of importance. I followed it for another three miles or so to the small village of Huang-tsao-ying, which with its luxuriant fields nestles cosily at the debouchure of the Hao -shan - k'ou gorge. Beyond the stream which issues from the latter, the wall runs on for half a mile more and finally climbs up the slope of a rugged rocky spur for some Zoo feet to where this becomes wholly unscalable.
It was interesting to examine how much care had been taken to defend also the triangular area formed by the mouth of the little valley outside the main wall. On the south a
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