When Richthofen journeyed in the Wutai district, Shan-si, he found a mighty sequence of metamorphosed sedimentary strata which could not be classed as his Sinian or any series younger than the Sinian, nor could it be regarded as belonging to the Old Gneiss and Gneiss-granite group. They are apparently equivalent to similar strata occurring in eastern Shan-tung and Liao-tung. In descending the Wutai-shan along its southern flank, Richthofen first came across a thick series of green schists with alternating beds of grey slates and quartzites, and then several series of coarse quartzitic and felspathic well-stratified rocks, aggregating to a thickness of more than 5,900 feet. He calls the whole sequence of these strata the “Wutai Formation”, and parallels it with the Huronian. This term at once found a wide application in Chinese geology. Thus in the western Tsing-ling Range, south of Lioyang-hsien (about long. 106° E., lat. 33° 25′ N.), and in the high mountains west of Ta-tsien-lu (about long. 102° 10′ E., lat. 30° N.), Loczy distinguishes a series of highly metamorphosed sedimentary rocks, such as gneiss, schists, phyllites, crystalline limestone, etc., and assigns it to the Wutai Formation. The “Nan-shan Sandstone”a series of unfossiliferous grey and green sandstones with well-cleaved or even schistose clayslates, typically developed in the northern foothills of the Nan-shan Ranges—is also tentatively regarded by the same author as a Wutai Formation. Between Ping-liang and Men-chou, in the province of Kan-su, Futterer identified in several places the Nan-shan Sandstone, and found other metamorphosed sedimentary strata of the Wutai Formation, consisting of chlorite-schist, coarse-grained quartzite, slate, and graywacke. In all these cases the term Wutai evidently implies the analogy with the Algonkian of North America.