426 RESEARCH IN CHINA. 
rock differs from the last described chiefly in having a greater proportion of 
quartz with less feldspar. Although numerous “‘augen”’ still inclose unre- 
duced sand-grains, the body of the rock is thoroughly schistose. Quartz 
and feldspar granules in parallel bands are associated with minute sericite 
flakes. ‘The ferruginous impurities in the original psammite have recrys- 
tallized in the form of magnetite. Judging from its composition the 
present schist represents an impure argillaceous quartzite which has been 
severely metamorphosed. 
PELITES. 
Gray phyllite, No. 101.—This slaty rock is one of the lowest recognized 
members of the Nan-t’ai series. It lies upon the jaspery ferruginous beds 
which mark the overthrust in the canyon of the T’ai-shan-ho,* south of 
Wu-t’ai-shan village. 
A dark-gray slate which cleaves into thin parallel lamine. It is com- 
posed largely of a dense argillaceous mass which has a pronounced schistose 
structure. The constituent minerals are chiefly sericite with micaceous 
hematite and granules of quartz. Parallel to the cleavage the rock is trav- 
ersed by lighter bands of coarser texture, which contain quartz and calcite 
with flakes of greenish biotite. All of the minerals occur also in eye-spots, 
as if they were original constituents of the slate. Biotite, however, is a 
characteristic product of anamorphism and we are disposed to regard it 
as of secondary origin. It may have been developed under earlier mass- 
static conditions and subsequently deformed by differential stresses. 
From the constitution of the phyllite we infer that it was formerly a 
calcareous shale. 
Purplish biotite schist, No. 86.—This represents a metamorphosed shale 
in the quartzite-and-schist sequence east of the T’ai-shan-ho. It is a 
member of the Shi-tsui series (Plate XVIII, stratum 9). 
A rather massive schist of purplish-gray color. 
Thin disk-like knots of coarse black biotite are scattered sparsely 
over the cleavage planes, but otherwise the micas are too minute to be 
readily observed. ‘The thoroughly schistose mass consists of parallel seams 
of quartz and feldspar granules with flakes of biotite and muscovite and 
abundant rectangular bits of magnetite. The micas are subordinate in 
quantity to the quartz, and they do not form interlaced seams except in 
the black knots referred to above. 
The rock is evidently a schistose pelite, derived, perhaps, from a red 
ferruginous shale. Nothing remains of the original components except 
certain crushed lenses of quartz which may have been sand-grains. ‘The 
argillaceous mass has recrystallized in parallel crystals adjusted to the 
2 Pattaly pile. 
