OBSERVATIONS IN CENTRAL SHAN-SI. 169 
extreme west of the range we had an opportunity, for the first time, to 
examine the material from it, which consisted of granite, gneiss, and basic 
intrusive rocks, without quartzites or limestones. This would indicate 
that the western end of the range, at least, exposes nothing but the basal 
complex. The quartzitic sandstone seen by von Richthofen resembles 
certain members of the Hu-t’o system to the northward, and is thought to 
be of Pre-Cambrian age. 
The front of the great range which extends from Tung-kuan westward, 
almost to Si-an-fu in Shen-si, and of which the Ta-hua-shan is the chief 
height, appears to consist wholly of the gneissic complex. ‘This impression 
was derived in the first place from the rugged irregular forms of the moun- 
tains. The Hua-shan itself seems to be composed of massive granite, in 
which joints are widely spaced and are at least partly vertical. Detrital 
material from the front of this range consists almost entirely of a variety 
of gneisses, granites, and other igneous rocks. The only exposure of the 
bed-rock which we examined is that at Lin-tung; there it proved to be a 
gray gneiss. 
PALEOZOIC. 
SINIAN SYSTEM. 
Like the preceding systems, the Sinian rocks are almost confined 
to the mountain groups. We did not see them along our route of travel 
in Shan-si south of the latitude of Ho-chéu. Stratified rocks of unknown 
character do, however, occur at high altitudes in the central portion of 
the Féng-huang-shan, and it is not unlikely that these may prove to be 
Sinian limestones. 
On the west side of the valley, between T’ai-yiian-fu and Tsin-tzi-chén, 
the upper part of the Ki-ché6u (Cambro-Ordovician) limestone is exposed 
beneath the coal-measures. At ‘Tsin-tzi-ché6n the limestones descend 
beneath the surface with a southwesterly dip, and do not reappear until 
brought up again by the monoclinal fold just west of W6n-shui-hién, where 
the entire Sinian sequence is probably exposed. 
In the mountain immediately east of Kié-hiu-hién, a part or all of 
the Sinian is brought up by a normal fault, provided our inferences as to 
the structure here are correct. In this place the base is apparently not 
visible. 
The Sinian makes just one appearance on the great road itself; at 
Ling-shi-hién a broad anticline raises the uppermost 100 to 200 feet, 30 to 
60 meters, of the Ki-chéu limestone into view beneath the coal-measures. 
The rock is a dense, dark-brown limestone of irregular fracture, resembling 
in all its details the Ordovician limestone, which is so wide-spread through- 
out northern China. 
