Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/218

 are found, as a general rule, forming the summits of the hills, while 2 and 5 almost invariably occur at the bottom of the valleys. In the Suichang district, near Kiukiang, of which a section is given (fig. 1), this arrangement is very marked ; from the summit A, about 900 feet in height, and composed of the cherty limestone No. 4, the lines of hills running from W. by S. to E. by N. form a peculiar feature, the landscape appearing like a mass of petrified billows following in suc- cession. At Nanking, as shown in the accompanying section (fig. 3), the series is similar ; but in this district the limestone is largely converted into dolomite, No. 4, however, being precisely similar in both locali- ties ; here, however, no such perfect section is obtainable as at Sui- chang, and it seems doubtful in some spots whether the dolomite should be referred to Nos. 6 or 8. The strike in this district is almost due E. and W.

Eig. 3. — Section of Coal-beds at Pah-hwei-miau in the NanJcing district. (Scale 4 miles to 1 inch.)

1. Grits. 2. Limestone, No 6. 3. Coal and Iron-shales, No. 5. 4. Limestone with chert-nodules, No. 4. 5. Shales and Grits, No. 3.

Proceeding eastwards for about 100 miles, we meet with the Tai-hu, a large lake in the prefecture of Soochow in Kiangsu province, which contains many islands composed of rocks of this formation. In two of these, the Tung and Si (East and West) Tungtings, the lower portion of the series is finely developed ; in the eastern portion of one, the Si Tungting-shan, of which a section is appended (fig. 4), the limestones come in lying, as before, conformably over the grits and shales of the lower series. As in the other districts, the bed No. 4, containing chert nodules in large numbers, is conspicuous ; further east for some distance a small alluvial plain interrupts the sequence, some low isolated hills seeming, however, to represent No. 5 ; while No. 6 appears further to the east in a bold promontory jutting out into the lake, where extensive limestone quarries have been worked for centuries.

These sections, with the foregoing description, will be sufficient to explain the general position and character of the lower sedimentary rocks of Southern China. As will have been seen, they are much disturbed, and in some localities altered by the intrusion of igneous rocks, which, especially along the coast chain from Macao to the Chusan islands, form in many localities the characteristic geological formation. Some of these localities have already been mentioned;