78 The American Geologist. August. 1904. 
the line of the great circle, but is decomposed into several more merid- 
ionally directed stretches, which, if one follows them from north to 
south, return to the average direction of the great circle by means of 
the equatorial stretches. Perhaps in this lies the basis for the fact that 
in northeasit Siberia, where the great circle in question makes only a 
small angle with the parallels the equatorial stretches predominate in 
their extent; the meridional stretches on the other hand become pro- 
portionately shorter and describe a larger angle with the meridian than 
they do farther to the south. Surely in that case the marked western re- 
treat from the south end of the Hukzvang fault forms part of an abnor- 
mal phenomenon and should be referred to some other cause. 
In the equatorial sections, also, there have been tectonic processes 
connected with the building out of the land-steps. Just here occur the 
great flexures directed toward the plain of Pekin, the embayment of 
Hwai-king-fn (Huai-king), and the northwest coast of the inner Yellow 
sea. However the transitions from the high grounds of the land-steps 
to the deep land stretches at their foot are made generally very grad- 
ually and are brought about through frequently changing mountain 
land-scapes. They appear to be more abrupt on the south side of Kii'ei- 
tscliou (Kui-chau) and Yuniiaii (Yunnan). 
C. TYPE OF TECTOXIC MOVEMENTS. 
a. Crescent-shaped border swellings with land depressed in front 
easily give rise to the impression of a movement on a large scale of the 
upper parts of the earth's crust from the interior of the crescent out- 
ward and connected with uplifting of the front as well as with interna! 
folds and overturns. Where this is found to be true there stand con- 
trasted with the phenomena of tension — fracture and sinking in upon 
the back side — compression within the circumscribed area of the zone 
of overturning, and hence the eruptive rock; are usually connected 
with the former. I have elsewhere shown* that the Tsin-Iing-schan 
(Tsin-ling mountains) owes its origin to such a movement directed 
from north to south, and, although the crescent form is in this case 
lacking, the phenomena mentioned are easily recognizable upon the 
north side. 
b. Of the crescent forms which are here under consideration, not 
one of those which lie to the north of the Tsin-liiig-sclwn (Tsin-ling 
mountains) appears to have the properties of a fold crescent. So far 
as observations are at hand they compel us to conclude that not com- 
pressive force from within outward but on the other han'd tensional 
forces which operated from the outside lie at the basis of the fault 
development. Step depressions, which we can prove in many cases, 
indicate by themselves an extension of space. But as alwaj-s in the realm 
under consideration where sections of a sediment plateau may lie at 
different levels near one another the simple explanation is always, so 
far as information goes, a sinking in of the deeper lying portion along 
» China, vol. ii, p. 655. 
