Baishangou Fm

East end of South Qinling tectonic region. The type section is located at Baishangou north of Wangguan village, about 12 km southwest of Xichuan County, Henan Province It was named by the south Henan Team of Regional Geological Survey of Beijing College of Geology, and was published by Regional Stratigraphic Scale of Central-South China in 1974.

Claystone, Sandstone. Lower part of the Formation is characterized by purplish-red shale and grayish-yellow quartz sandstone, with a bed of purplish-black conglomerate (0.97 m thick) at the base. It is 110 m in thickness. Middle part consists of purple thin-bedded mica-bearing fine-grained feldspathic quartz sandstone and is 160 m in thickness. Upper part is composed of yellow clay intercalated with thin-bedded sandstone and sandy shale, 130 m thick. At the top, there is a bed of grayish-white fine-grained quartz sandstone.

The lithology of the formation is relatively uniform, but the thickness greatly varies, getting thicker from the west to the east. In the west, at Hutou of Xichuan area the formation is only 83 m thick, but east of Laoguan River to Hulushan of Neixiang area, the thickness reaches about 400 m.

The bivalve Cypricardinia occurs in the middle part of the formation.

It is interpreted as a littoral environment, based on ripple marks and cross-bedding in the sandstone beds.