The notable torsion effects of the surface ground motion above the alluvial valley are illustrated and the torsion effects become stronger as the frequency of the incidence is higher.

Comparison analysis for antiplane surface motion features between the circular-arc cross-section alluvial valley and the single overburden layer is investigated in details in this paper.

The studied platinum - gold placer occurs in Quaternary alluvial - diluvial a piedmont valley of ultrabasic rocks, Northwest China.