STRATIGRAPHY OF SHAN-TUNG. 55 
gray in color, and contain the only vestiges of fossils found anywhere in 
the Sin-t’ai series—black bituminous impressions of fragments of unrecog- 
nizable plants. This gray member of the series is at least 250 feet thick. 
The uppermost portion of the Sin-t’ai series comprises brick-red, or 
rarely grayish, clays, sandy silts, and conglomerates. Like the rest of the 
formation in this section they lie inclined 20° to 30° toward the north. 
If this dip is all due to the subsequent tilting of sediments which had 
been deposited in a horizontal attitude the clays are not less than 8,000 
feet, 2,400 meters, thick. It is possible that some of the inclination was 
conditioned by deposition of sediments on a sloping surface, but the uni- 
formity of the dip over several square miles, and its coincidence with the 
dip of the underlying Sinian limestone are evidences which tend in some 
degree to controvert that hypothesis. The upper red strata themselves 
are soft massive sandy clays, usually without shaly cleavage, interspersed 
with sandstones and thin seams of gray and green clays. ILll-defined bands 
of calcareous nodules, like those occurring in the recent loess deposits, are 
frequent along the bedding planes. At one place, 4 miles west-northwest 
of Sin-t’ai, the red clays even contain limestone in isolated strata, % to 
2 feet in thickness. The rock is creamy white, cryptocrystalline, and 
breaks in all directions with an irregular or conchoidal fracture. It seems 
to be barren of fossils and is unlike any other rock seen in the province. The 
conglomerates occur in thin strata at frequent intervals and at almost 
all horizons in the red clays. The constituent pebbles, ranging up to 
4 inches in diameter, comprise a variety of rocks. The commonest are 
dark gray limestones of the Sinian system, but there are also pebbles 
of black quartzite and hornblende-porphyry—the former a rock which 
was not found im situ during our sojourn in Shan-tung. The matrix in 
which these pebbles are embedded is variable. Frequently it is red and 
sandy; more often the pebbles are interstratified with the red clays directly, 
while, in cases, the matrix is calcareous and forms a creamy pink rock, 
filled with the dark angular pebbles of limestone, etc. Whatever may 
have overlain the red clays in this section has been cut off by a normal 
fault of large throw, which traverses the northern side of the valley. 
So far as our observations go, evidences of volcanic activity in the 
Sin-t’ai area are confined to a single dike about 4o feet, 12 meters, wide, 
which cuts the lower red sandstone about 4 miles south of the city. 
This is so badly weathered as to be difficult to recognize in the field. It 
shows spheroidal parting ina soft, decayed, grass-green mass, and in the 
centers of the spheroids there remain hard nuclei, which prove to be por- 
tions of the solid lava. These nuclei were formerly composed of a dark 
