Abstract:

The western United States and southeastern China, featured by landscapes of red cliffs, are major distribution regions of red beds in the world. It is of great value to make a comparative study on red beds and landform development in these two regions. Based on geologic literature analysis and field investigation, this study summarizes the distribution, age, geologic background, lithology, and geomorphic features of red beds in the western United States. Then, a comparison with Danxia landform in southeast China was conducted. It reveals that red bed landform in the western United States and Danxia landform in southeast China are erosional landform developed on red beds, with red cliffs as a remarkable geomorphic feature. However, due to differences in regional geologic background, material basis, and the dominant exogenic force, specific geomorphic features in these two areas are not exactly the same. Red beds in the western United States were mainly deposited in a huge back-arc basin during the period from Triassic to Jurassic. Although depositional environment for these red beds are complex, most of them are continental deposits, especially eolian deposit. In terms of lithology, the majority of red beds in the western United States are composed of fine-grained sandstones, siltstones or mudstones, with very few conglomerates. In terms of geomorphic development of red beds in this region, the downcutting process by flowing streams has been playing a dominant role, creating relatively simple red bed landform types that are characterized by a geomorphic combination of plateau and canyons. As for Danxia landform in southeast China, red beds were deposited in Cretaceous in small and medium-sized rift basins or depression basins. They are all continental deposits, mainly composed of coarse-grained clastic rocks. In aspect of landform development, the controlling exogenic factor is lateral erosion by streams, which produces various types of red bed landforms, with peak clusters and hoodoos as overall landscape feature.

Key words: red beds, Danxia landform, western United States, southeastern China, comparative study