436 RESEARCH IN CHINA. 
phosed than the majority of the Wu-t’ai rocks. The schistose conglomer- 
ates (97) of the Si-t’ai series resemble the present rock in some particulars, 
but even they have been more severely metamorphosed and are probably 
much older. 
Specimens from the spur at a point 2.25 miles, 3.6 kilometers, south of 
the village of Fang-lan-ch6én, Shan-si. 
This is an arkose or graywacke of coarse grain, which contains pebbles 
of various sizes up to 8 inches in length. The majority of the pebbles 
are of quartzite, but the list also includes gray phyllite, chlorite schist, 
scapolitic biotite schist (158), and vein quartz. ‘The matrix in which these 
pebbles are embedded has a greenish-gray color, modified by the presence 
of numerous bits of pink feldspar. The rock is indistinctly banded and the 
pebbles lie with their broad sides parallel to the bands. Although the evi- 
dence of mechanical deformation is plain, true schistosity is only incipient. 
The pebble in No. 106 is a pure quartzite which consists almost wholly 
of rounded grains of clear quartz, cemented with the same material. The 
grains show strain-shadows, but they have not been fractured, and even the 
cement has been only slightly granulated. In No. 107 the only large pebble 
is a soft, dull-gray, sericite slate or phyllite (slide 107-c), of which the only 
plainly visible components are a few grains of quartz. 
The matrix of the conglomerate is an indurated arkose which shows 
only traces of schistosity. In No. 107 it consists of rounded and subangular 
grains of quartz and feldspar distributed rather sparsely in a ground-mass 
composed of minute particles of colorless micaceous minerals, quartz, and 
iron oxides. The quartz and feldspar grains are strained and occasionally 
fractured; and, at certain points of contact, granulation has occurred. 
No. 106 was more severely metamorphosed. The matrix has a distinct 
though poorly developed schistose structure. Several of the larger sand- 
grains are followed and preceded in the line of schistosity by granulated 
areas, but in general these ‘‘eye-spots’’ are not well defined. In some 
of the mashed areas small secondary crystals of microcline have begun to 
appear. Magnetite occurs in angular grains, many of which have changed 
to pseudomorphs of martite. Earthy hematite also fills many of the 
fractures in the sand-grains and occurs with limonite as a reddish-brown 
pigment in the microscopic shear-zones. Locally the ground-mass contains 
clusters of minute purplish-brown tourmaline laths, which are evidently of 
secondary origin. 
PSAMMITES. 
Impure sandstone, No. 104.—Hard quartzitic sandstones of purple, 
pink, and gray colors lie upon slates and beneath conglomerates in the north 
end of the ridge east of Tung-yii. The relations suggest that the series is 
