Geologically, the rock mass of the Mogao Grottoes is semi-binder calcirudite of the quaternary sediment of very loose structure.

莫高窟岩体在地质学上属第泥质、钙质半胶砾岩，构十分松散。

Mainly developed are fan - delta, deep lake turbidite and calcirudite deposit, and also alluvial fan deposit in early period.

各时期形岩和粒屑灰岩储集体,为油气储集提供了有利场所。