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

莫高窟岩体在地学上属第四纪沙泥、胶结砾岩，结十分松散。

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

各成的砂岩和粒屑灰岩储集体,为油气储集提供了有利的场所。