Zhaogezhuang Fm

The type section is located at Zhaogezhuang, about 20 km by north of Tangshan, Hebei. It was named by Grabau in 1920.

Sandstone, Coal and Claystone. Lower part consists of light-gray medium- to coarse-grained sandstones, containing quartz and chert pebbles, turning into dark-gray mudstone and siltstone in local members, containing 3−4 coal seams, called Coal-11, Coal-12 Top, Coal-12 Bottom and Coal-12 Lower ascending. The last one is partly mineable, while all the others are the main mineable coal seams. Upper part is dominated by dark-gray mudstone and siltstone, occasionally intercalated with gray fine-grained sandstone. 25−74 m thick.

Claystone in Lower part of Coal 11 contains Plants Rhacopteris rartrandii, Neuropteris ovata, Alethopteris kaipingiana, Tingia carbonica, Pecopteris feminaeformis, Sphenohyllum oblongifolium, etc.; The dark-gray claystone in the Upper part yields Brachiopod Lingula myliloides; Bivalves Pseudomonotis sp., Parallelodon sp., Sanguinolites sp., etc.;