Original paper

Weathering pattern and development process of bedding-controlled caves at Mt. Danxiashan, China

Hua, Peng; Zhixin, Pan; Zhuowei, Qiu

Abstract

Bedding-controlled caves, characterized by rapid weathering of soft intercalated rock layers, are a type of negative landform widely distributed in the Danxia landform area. Based on field investigations, three typical bedding caves were selected as case studies. This study involved field survey of the development conditions and weathering features, followed by collection of rock samples, rainwater and ground water samples for further laboratory tests. Soft interlaid rocks between layers generally belong to silty mudstones with high contents of clay minerals and argillaceous cements. Due to their strong absorbability, high porosity and low compressive strength, these soft rocks are vulnerable to weathering and easily broken into smaller pieces. The overlying and underlying rock layers are more resistant sandstones or sandy conglomerates, with large particles, cemented mainly by calcite and iron oxides, low porosity and higher compressive strength. The weathering pattern and development process of Danxia bedding caves is described as occurring in the following stages: exposure of soft interlaid rock layers – formation of microcracks – expansion of microcracks and exfoliation of rock fragments – continuous weathering and recession of soft interlaid rock layers – formation of initial caves – enlargement of caves – destabilization and collapse of overlying rock – cliff retreat.

Keywords

danxia landformslandform evolutionweathering patternbedding-controlled cavessoft red bed intercalations