II4 RESEARCH IN CHINA. 
the cleavage surfaces are sericitic. The schistose quartzite associated 
with the arkose shows all variations, from fissile gray quartzite to finely 
laminated quartz-sericite-schist with pearly cleavage planes. By increase 
in the amount of chlorite these quartzose schists pass insensibly into the 
green schists beyond. 
The great mass of the Wu-t’ai-shan consists of chlorite-schists, which 
exhibit minor variations in mineralogical character, but nevertheless 
are essentially monotonous in constitution. The surface is, to a great 
extent, covered with residual soil and to some degree with loess. Under 
these circumstances the measurement of detailed sections, such as we 
observed in the canyons of the T’ai-shan-ho and its tributaries, was not 
attempted in the mass of the range. 
We made general observations in the vicinity of the village of Wu-t’ai- 
shan, along the summit ridge north of it, on Nan-t’ai, in crossing the passes 
toward Liu-yiian and Yen-t’ou, and in the canyon of the stream which flows 
past Yen-t’ou, the O-shui-ho. 
Von Richthofen considered the green schists the most characteristic 
rocks of the system, and, so far as our observations extend, a large part of 
the mass consists of chlorite-schists unassociated with any other rocks. In 
themselves the schists exhibit several phases which may be distinguished. 
In some cases they are massive, not well cleaved, and distinctly argilla- 
ceous in composition; chlorite is not visible in this variety, although its 
presence in a finely divided condition is inferred from the color. Elsewhere 
are slaty schists or phyllites, with lustrous green surfaces covered with 
chlorite; in fact this variety appears to consist almost entirely of that 
mineral. In other phases the chlorite is mingled with biotite, and again 
with quartz, in thoroughly schistose masses of green color. 
From these descriptions it is evident that the quartzose rocks of the 
Wu-t’ai series are metamorphosed sediments. The derivation of the 
chlorite-schists is not so obvious, but since they appear to grade directly 
into the schistose quartzites and possess a mineral constitution which 
could readily have been derived from the metamorphism of clay rocks, 
it seems reasonably certain that they too were sediments. 
Occurrence of conglomerate on Nan-t’ai.—The slopes of Nan-t’ai consist 
chiefly of the siliceous marbles, jaspers, and quartz-schists of the southern 
part of the Wu-t’ai section, but the summit is a mass of chlorite-schist over- 
lying a bed of coarse conglomerate, which contains pebbles of quartzite, 
quartz, and granite. This conglomerate thus corresponds, both in consti- 
tution and stratigraphy, with that seen in the main range. It lies at a 
gentle dip of 30° to the northwest, and appears to be a synclinal remnant 
of the highest formation remaining in the peak of Nan-t’ai. 
