ROCKS FROM NORTHERN AND CENTRAL CHINA. 391 
the pebbles contain many small chips of fossils, but the great majority are 
entirely barren. 
No. 45, from the same place as Nos. 46 and 47. The pebbles are 
clear-gray limestone set in an ocherous matrix. The bodies are generally 
long and are rather more angular than in the previous specimens. 
No. 48, from the same place. This is noteworthy chiefly because 
most of the pebbles are very small and many of them angular. Both 
pebbles and matrix are of a clear-gray color and the red ferruginous borders 
are either very narrow or entirely absent. 
No. 157, from the Man-t’o shales, near the village of Mei-yii-shan, 
south of Po-shan. A dark maroon-red rock in which there is no distinction 
in color between the pebbles and the matrix; in fact, the former are scarcely 
visible except on weathered surfaces. Under the microscope it is found 
that the pebbles consist of fine-grained limestone, being rather closely 
packed and cemented by limestone which contains abundant grains of 
quartz sand and bits of iron oxide. Both the pebbles and the matrix are 
filled with finely divided red hydrous hematite which imparts the dark 
color to the rock. 
ORDINARY LIMESTONES. 
Under this heading we have grouped a number of fine-grained dark 
limestones which represent several different terranes in the Sinian system. 
Some of them are entirely aphanitic and of uniform color; some are mottled, 
while others contain visible crystals of calcite and in some cases fossils. 
Dense brown limestone, No. 9.—A characteristic phase of the Tsi-nan 
(Ordovician) formation in Shan-tung, and of the corresponding terranes 
in Manchuria and Shan-si. Specimen taken from the base of the Tsi-nan 
limestone at Ch’au-mi-tién. 
A brown rock of aphanitic texture. It fractures irregularly and is 
cut by numerous small calcite veins and so-called ‘‘blind joints.’’ This 
specimen contains no trace of fossils, and they are exceedingly rare through- 
out the formation. 
Dense gray limestone, No. 7.—Specimen secured from a stratum 50 
feet above the base of the Ch’au-mi-tién formation, near the village of that 
name. Like the next, this is one of the hard ringing gray limestones which 
are so common in the middle Cambrian series of eastern China. 
The color is rather dark gray and uniformly plain. As in most other 
dense hard limestones, the habit of fracture is conchoidal. The strata 
are separated from each other by shaly partings of a light-green color. No 
fossils have been found in it. 
Dense gray limestone, No. 6.—Thin limestone seams in green, purple, 
and yellow shales of the Ku-shan formation, in the type locality. 
