PHYSIOGRAPHY OF SHAN-TUNG. 83 
get at the deeper deposits we could probably fix the date of beginning of 
warping; but no deep wells have been sunk, and throughout the plain 
only recent alluvium isto be seen. The latest deposits cover all earlier ones, 
partly in consequence of the abundant sediment derived from the loess, 
and also because continued subsidence has brought a wider area down 
to the level of the flood plains. 
Shan-tung a horst.—Has recent warping resulted in elevation or depres- 
sion of the central mass of the dome? In Shan-tung the answer to this 
question appears to be that the central mass has remained at a fixed 
altitude with reference to sea-level, while the margins have been depressed. 
We have seen that the principal differences of elevation in the western 
mountain district of Shan-tung are the results of faulting, which date 
from an early Tertiary time, and which have been modified by prolonged 
erosion. Partly in consequence of faulting and partly as a result of erosion, 
the valleys are very broad and low. They could not have been eroded 
to the present level had the mountain area formerly stood notably lower 
than now; neither could they have retained flat and aggraded valley floors 
if the area had recently been elevated. The condition of the valleys 
proves that, for a long period, the mountain district has remained nearly 
fixed with reference to sea-level. It has been a true “horst.’’ During 
part of this cycle of erosion, and up to the latest, if not to the last, episodes, 
the surrounding districts have subsided; they have been warped down. 
Thus the mountain region of Shan-tung may be described as a horst 
surrounded by downwarps. 
