46 RESEARCH IN CHINA. 
South of the Siau-w6n-ho, in the longitude of Sin-t’ai-hién, two species 
of similar character were collected from massive limestone estimated to 
be 300 to 500 feet, 90 to 150 meters, below the top of the Tsi-nan formation: 
Orthoceras sp. undt. Gastropod undt. 
Equally imperfect and rare fossils were observed at several other 
localities in east China, viz, at Po-shan and Yen-chuang, Shan-tung, and 
at the T’ang-shan coal-mines in Chi-li. 
IN THE PO-SHAN DISTRICT. 
As exposed near Po-shan the Tsi-nan formation presents no new 
peculiarities. The city itself stands upon the eroded surface of the upper- 
most layers of the Tsi-nan limestone. Immediately to the southeast a 
normal fault drops the formation below the surface and thus preserves 
a portion of the overlying coal-measures. The limestone soon reappears, 
however, from beneath the Po-shan strata, and is exposed in a nearly 
horizontal position for a distance of about 10 miles, 16 kilometers, south 
of the city. 
IGNEOUS ROCKS ASSOCIATED WITH THE SINIAN SYSTEM. 
We saw no evidence of volcanic activity which was contemporaneous 
with the deposition of the Sinian rocks. All the igneous rocks occur as 
dikes and sills, and, except for the obvious fact that they are younger 
than the terranes which they penetrate, there is nothing from which 
trustworthy conclusions as to their age can be drawn. However, it is 
notable that most of these dikes are petrographically similar to intru- 
sions in the Permo-Carboniferous system, and it is therefore probable 
that the dikes which cut the Sinian rocks date from the same period of 
volcanic activity. 
Sills and small laccolitic masses of hornblende-syenite-porphyry are 
frequently found in the lowest beds of the Man-t’o formation. ‘The soft 
shales probably yielded readily to the pressure of the intruding magma 
as it was forced into the sedimentary rocks. In the mountain east of 
Ch’ang-hia, the Man-t’o shale contains several sheets of a gray-green syen- 
itic lava, the phenocrysts of which were formerly cruciform crystals of 
hornblende, but are now replaced by calcite and other alteration products. 
These sheets range in thickness from a minimum of 1 foot up to 25 
feet. Two dikes, respectively 5 and 12 feet across, rise higher in the 
Sinian, the latter cutting the Ch’ang-hia oolite a few miles northeast 
of the village of the same name. Like the sills, they too are syenitic. 
In the Sin-t’ai district, rocks bearing a general similarity to these were 
seen in the basal Man-t’o shales, and also near the top of that formation. 
One and one-half miles, 2 kilometers east of Kau-kia-p’u there is a laccolitic 
