CHAPTER X 
GEOLOGICAL NOTES 
EOLOGICALLY the country traversed on 
the various journeys described in this book 
may be divided into two sections, separated 
roughly one from the other by the outer loop of 
the Great Wall. 
South of this line, in Chihli and Shansi, the 
outcrops are chiefly of sedimentary rocks, with here 
and there masses of the underlying plutonic and 
metaniorphic rocks showing through. Thanks 
to Baron von Richthofen and Bailey Willis these 
rocks are pretty well understood, and there re- 
mains only the work of recording their occurrence 
in different localities, and any other geological 
phenomena hitherto unobserved. These stratified 
rocks extend westward and northward across the 
Ordos, North Shensi and well into Kansu, and 
also up to the extreme north-west of Shansi. 
North of the outer loop of the Wall the outcrops 
are entirely igneous and metamorphic, granite, 
trachyte, basalt, porphyry, gneiss and_ schist 
occurring in great confusion, so that considerable 
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