158 RESEARCH IN CHINA. 
to be modified by broader investigation, and we have presented our 
deductions with appropriate qualifications in the preceding chapter. 
Summarizing them, we may make the general statement that certain 
repetitions of strata in inverse order, in connection with dips that converge 
downward, suggest closed synclines, while other repetitions in regular order 
are attributed to overthrusts. 
The Shi-tsui series (see Plate XVIII) is apparently duplicated on 
the limbs of a syncline. The Shang-ho-miau section presents several 
folds which were in part observed in the field. Nan-t’ai and the southern 
slope of the main Wu-t’ai range consist of a partial syncline, of which 
the northern half is lacking. In adjacent crests of the main ridge the 
sequence is in part repeated in identical order, but it there includes 
the higher schists; and on the northern slope there is a further repetition 
of the same upper strata in the same order. 
If our interpretation be correct, the Wu-t’ai system occurs in this 
section with a shingled structure (Schuppenstruktur) of which the south- 
eastern element, the Shi-tsui series, includes the oldest strata and in which 
each element toward the northwest takes in higher and higher strata. A 
similar structure is found in the unaltered Paleozoic rocks of the southern 
Appalachian province.* 
Folding oj the Hu-t’o series.—The argillites and limestones of the 
Tung-yii series are sharply distinguished from the Wu-t’ai schists, in consti- 
tution and structure. They are but slightly metamorphosed and are clearly 
recognizable sediments. They are schistose only where their composition 
is that of clayey rocks especially liable to the development of cleavage 
or where the local conditions of pressure were exceptional. They occur 
in the Wu-t’ai district in a broad synclinorium, within which there are 
many minor folds, usually of a somewhat open character. The pitch of 
these folds is toward the southwest, and in accordance with this general 
fact it is inferred that the older strata of the series were found in the 
northeastern exposures, and the younger strata further southwest. If so, 
the lower part of the series consists chiefly of argillites and the upper of 
gray cherty limestones. The latter lie along the central portion of the area 
and the distribution of members within the basin conforms to a central 
synclinorium, margined by an anticlinal belt on the south and overthrust 
by a complexly folded belt on the north; but the minor structure is so 
complex and of such importance that the actual distribution is probably 
much more intricate. Anticlines and overthrust limbs of the lower strata 
no doubt appear in the area which we have mapped as composed chiefly 
of the limestone; and synclinal masses of the limestone no doubt occur 
* See the Cleveland folio, Geological Atlas of the United States. 
