The Mesoproterozoic Wumishan Formation in Jixian, Tianjin represents a succession of 300-m thick carbonate strata, in which stromatolite biostromes and clotted bioherms are best developed.

• 天津蓟县中元古界雾迷山组为一套厚3000余米的碳酸盐岩地层，叠层石生物层和凝块石生物丘特别发育。