16 J. S. Lee — Recent Ice- Action in iV. China. 



Pasquier, and others that an avalanche sometimes slides down hill- 

 slopes like a landslip, and heaps up masses of fragmentary rock or 

 boulders in the valley. ^ Moreover, it is well within all possibilities 

 that some of the fragmentary rocks had already undergone a j)rocess 

 of rubbing before they were transported by the ice. 



The boulders largely consist of sandstones of many kinds. Some 

 of them are members of the coal-bearing series, others are foreign 

 and unknown in origin. A green tufi-like sandstone and a hard 

 quartz-sandstone frequently occur in huge blocks wdth one side well 

 polished. The former is entirely unknow^n in the surrounding 

 country ; the latter caps the hills to the south-east of the 

 Sha-yuan-ling, and extends discontinuously for more than 60 miles 

 southward. Cherts and wind-faceted pebbles are now and then 

 found among the more comminuted material. Well-rounded 

 qaartzitic pebbles of the size of Easter eggs rarely occur, and 

 appear to be limited to the upper part of the deposit. The Sinian 

 Limestone which forms the high range of the Tai-hang to the w^est 

 is singularly absent ; while the presence of the hard quartz-sand- 

 stone, dolerite, etc., indicates that a part of the boulders are of 

 local origin or arrived from the south. 



The deposit rests upon a denuded anticline, pitching slightly 

 towards the north-east. The exposed part of the anticline con- 

 sists of a buff sandstone which lies well above the zone of 

 Pterophyllum carhonarium Schenk.^ Above the deposit there is 

 a mantle of loess. As far as can be judged from the suggestions 

 of stratification, both the loess and the rock immediately under- 

 lying it are slightly arched in a conformable manner. No signs of 

 erosion were detected in the contact plane of the two, though sharply 

 defined. Thus it appears that there has never been any violent 

 tectonic disturbance, but possibly a pre-loess landslip or avalanche 

 that might have given rise to the striation on some of the boulders. 

 But landslip alone cannot explain all the observed facts. 



A hummocky hill forms the eastern portion of the Sha-yuan-ling. 

 The upper part of it is composed of dolerite, probably in the form 

 of a laccolithic intrusion. A few but conspicuous strange boulders 

 lie here and there on the hill-top like ruins of great antiquity. 

 Polished and scratched or grooved surfaces are seen everywhere. 

 These differ in many respects from the curious grooves that have 

 been occasionally noticed on the igneous intrusions in the South 

 Staffordshire coalfield and elsewhere. The latter, for instance, 

 are usually irregular and slightly wavy or curved, while the lines 

 or grooves on the loose fragments of the dolerite of the 

 Sha-yuan-ling are not only of frequent occurrence on the whole 



^ Coaz, Die Laivinen in den SchweizerAlpen, Berne, 1881. Heim, Die 

 Gletscheriaivine an der Altels am 11 Sei^temher, 1895, Zurich, 1895 

 (N. N. G. Z., 1896), pp. 11-17. .Pasquier, L'Avalanche de VAltels le 

 11 Septembre, 1895, Neuenburg, 1896. 



^ China, vol. iv, p. 214, pi. xliv, figs. 4, 5. 



