8 GEOLOGICAL RESEARCHES IN 



and this is the case with all the exposed sections from the outlet to the Siauku shan 

 or Little Orphan rock. Below Tungliu coarse red sandstone is exposed, its upturned 

 edges, which are here capped with the younger terrace deposits, trending to N. E. 

 with a dip of 15° to N. W. At Nanking there are extensive quarries of limestone, 

 whUe directly opposite the city, on the left bank of the Yangtse, strata of red sand- 

 stone trend W. S. W., dipping about 40° to E. S. E. Coal mines are worked in 

 the immediate neighborhood of this city, especially on its eastern side. Soon after 

 leaving the hills of Nanking the river enters the great delta plain through which it 

 winds to the sea. 



In a resume I shall try, by means of a combination of the data given above, with 

 information derived chiefly from native sources, to throw more light on the structure 

 of this region. 



TERRACES OF THE YANGTSE VALLEY. 



At frequently recurring points along both the Upper and Lower Yangtse, we 

 meet with deposits of gravel and clay, forming blufi's at the water's edge, or fringing 

 the hills that form the walls of the valley. They are generally stratified in 

 horizontal beds. Differing in height and in the character of their ingredients, there 

 seems also to be a diversity of age. The extensive plain, once occupied by the 

 Tungting lake, before it was reduced to its present size, is fringed by these terraces; 

 for they recur constantly from Hankau to Yochau on the right bank of the river, 

 and from this city along the eastern border of the lake, and form a belt which 

 extends many miles to the south, and occupies nearly all the space along the south- 

 ern edge of the lake, between the Siang and Yuen rivers. Again, where the river 

 enters the lake plain, the tongue of land included by the river bend between Pah- 

 yang and Tung'sz, consists of the same deposit. 



At the last named locality the deposit is made up of rounded pebbles of quartz 

 and limestone, cemented with a stiff clay, and this is its general character at the 

 junction of the Siang river with the lake and along the eastern shore. But the 

 most general form of occurrence is that of a stiff blue clay, with irregular white 

 spots. Near Tung'sz the terraces appear to be from seventy to ninety feet high, 

 but below the outlet of the lake they vary from thirty to sixty feet. Blackiston 

 mentions similar terraces as occurring at various points along the Yangtse ha 

 Sz'chuen. 



The village of Tsingtan, at the eastern end of the Mitan gorge in Western Hupeh, 

 is built on a terrace of conglomerate-breccia formed of fragments of limestone, 

 chert, gneiss, and other metamorphic rocks, in form of rubble and rounded and 

 angular fragments of all sizes, the whole firmly cemented by a calcareous tufa. 

 This formation originally filled the valley from side to side, and its bluffs rise forty 

 to fifty feet above high-water mark. In the rapid current that must always have 

 scoured these narrow portions of the Yangtse valley, nothing but the coarsest 

 material could resist the onward movement ; and when an increase in the A'elocity 

 of the stream took place, only those portions of the deposits were preserved which 



