LOESS WEST OF SECOND RANGE 133 



In one of these valleys, near th£ Mongolian escarpment, there was 

 especially clear evidence of the recent cessation of the agencies which 

 had been distributing the loess in its normal quantities. This was 2 

 miles above Hanchinbah, in the first stream east of the escarpment, run- 

 ning southwest between mountain ranges about 2,000 feet higher than 

 the valley. Here is a bluff of loess about 40 feet in height, and/ ex- 

 tending back from the stream in a well defined terrace for a considerable 

 distance, yet it was exposed to the direct force of the stream in a con- 

 cave bend with its unprotected perpendicular face to the stream. The 

 stream bore every mark of being at times torrential, its bed being full of 

 large boulders, some from 4 to 5 feet in diameter, all in slow process of 

 transportation down the stream. The gradient of the stream here was be- 

 tween 100 and 200 feet per mile. That so large an expanse of loess 

 should have been accumulated to such an extent by present agencies, or 

 should have remained in this unprotected position for many thousand 

 years, would seem improbable, not to say impossible. 



Gravel Banks near Hanoor 



On the road from Kalgan to the summit of the Mongolian escarpment 

 at Hanoor, there is an immense accumulation of gravel near the base of 

 the escarpment, about 2,000 feet below the summit and about 3,000 feet 

 above the sea. This has been well described by Pumpelly and its puz- 

 zling character fully recognized by him. The road extends through it 

 for 2 or 3 miles, the gravel banks rising on either side to a height of 

 from 100 to 200 feet. On ascending the banks, the surface is found to 

 be nearly level, though having been subjected to considerable erosion. 

 On the southwest side, the outer Chinese wall follows the summit of the 

 gravel for a considerable distance as it climbs upward toward the escarp- 

 ment. On the northeast side the deposit has a breadth of 2 or 3 miles, 

 appearing, according to Pumpelly, on one of the parallel roads coming 

 down to Kalgan from the plateau. When first encountering this gravel, 

 we felt confident that it was an overwash deposit from a glacier which 

 had covered the interior, and temporarily, when melting, poured its tor- 

 rents down from the face of the escarpment ; but on reaching the plateau 

 and traveling many miles along its border, there were no signs that ice 

 had ever covered the region. For a considerable distance to the interior, 

 the border of the plateau here consists of a basaltic overflow which has 

 obscured everything underneath, and the slope begins almost imme- 

 diately to be directed toward the interior, nor are there any signs of even 

 temporary lines of drainage across the escarpment to the east, such as 

 might have been produced by glacial ice obstructing the natural western 

 drainage lines. 



