OF ARTS AND SCIENCES : MAY 25, 1869. 117 



one or two feet thick. There is a remarkable regularity in the 

 occurrence of this bed of coal, and of the entire formation, with its 

 lydite and other distinguishing features, over a. wide extent of country. 

 I found it in places four hundred miles distant from each other. The 

 thickness of this formation is about four hundred feet. 



c. Upper limestone. It is separated from the coal only by a thin 

 stratum of black shale, and is similar in nature to the lower limestone. 

 I observed its thickness for sixteen hundred feet, but never saw its 

 upper portion. 



The thickness of the entire formation is thus at least three thousand 

 four hundred feet, but I am prepared to see it proved to be several 

 thousand feet thicker by future observation. The Kitau limestone 

 composes entire mountain ranges by itself alone, chiefly between Kiu- 

 kiang and Han-kau. Kingsmill mentions, as overlaying the Tung-ting 

 sandstone of the Liu-shan to the west, a limestone formation of an 

 estimated thickness of six thousand feet ; it is probably altogether 

 Kitau limestone. 



9th. Sanghu sandstone and conglomerate. — The deposition of the 

 Kitau limestone ended with a considerable disturbance, as the next 

 formation follows quite unconformably. It consists of quartzose sand- 

 stone and quartzose conglomerate, interstratified witli thick layers of 

 red clay, and carries a coal-bed at a place sixty miles below Han-kau. 

 Black shales, which overlie the coal, carry some remains of plants. I 

 was unable to establish the thickness of this formation. 



10th. Commencement of the outbreaks of porphyry. — The porphyritic 

 eruptions have probably continued in China during a long period, 

 while sediments were contemporaneously deposited. Pumpelly was 

 the first to direct attention to these wide-spread events. But it is only 

 in the great granitic region of the eastern coast, between Ningpo and 

 Hong-Kong, that porphyry itself arrives at an extraordinary develop- 

 ment. The Chusan Islands are almost exclusively composed of 

 quartzose porphyry and its tufas, and from there southward it appears 

 to be only subordinate in quantity to the granite. I know it from my own 

 observations on the island of Hong-Kong, and by inference from the 

 observations of others, of the region between that island and Ningpo. 

 This is the most extensive development of porphyry known in any 

 part of the world. 



11th. Deposits of porphyritic tufa, sandstones, and clays. — The 

 porphyries themselves are little developed on the lower Yang-tse. I 



