Loess Sinkhole Landscape or Loess Collapse Hole Landscape

This is a loess subsidence landscape. Dish-like depressions develop in loess and subside, forming loess collapse holes of great depth and width. This landform results from the combination of dissolution and mechanical erosion. Based on the form, loess collapse holes can be divided into shaft-like, funnel-like and beaded string-like holes. The diameter of a shaft-like hole’s mouth can reach several metres, and the depth can be up to 20–30 m. Funnel-like holes have larger mouths but small bottoms, like a funnel, and can be several metres deep. Beaded string-like holes contain several collapse holes connected by subterranean tunnels. These tunnels are straight with a gentle gradient and some are also temporary waterflows. When subject to further erosion and the effects of gravity, beaded string-like sinkholes can evolve into loess gullies. Loess collapse holes are a spectacular loess micro-landform (Fig. 42).

Fig. 42

Loess sinkhole landscape – Yongdeng, Gansu Province