6 GEOLOGICAL RESEARCHES IN 



useful and choice marbles. Every degree of tliickncss occurs in the layers from 

 laminae only one-quarter inch thick to beds of many feet. 



Nodules and thin hiyers of black chert occur throughout the limestone, but in 

 the lower half they are remarkably frequent, becoming more common as we ap- 

 proach the oldest beds, in which, indeed, the calcareous rock is often entirely 

 excluded by massive layers of quartzite. At the eastern entrance to the Lucan 

 gorge, where the limestone rests on the older rocks, the lowest beds of the former, 

 containing lenticular masses and thin layers of chert, are soon succeeded by a bed 

 40 to 60 feet thick, of massive quartzite. 



Wherever I have had occasion to examine this limestone in place, it has invaria- 

 bly appeared to be entirely without fossils, but this has been only in the main 

 ridges, where metamorphic action has probably played a more important part than 

 in the minor ridges that rise between these lines of greater elevation, and it seems 

 to me that there can be little doubt that the fossil Brpchiopoda that occur in many 

 provinces belong to this formation. "^ ' 



Just before entering the eastern mouth of the Lucan gorge, a bed of fine-grained, 

 micaceous, gray sandstone is observable, intervening between the metamorphic 

 schists and the limestone. The trend of this intervening bed is N. N. W. and the 

 dip 25° to 30° to W. S. W., the metamorphic schists striking to E. N. E. and 

 dipping to N. N. W., while the trend of the overlying limestone strata, at the nearest 

 point observed, was about N. by W. and the inclination about 30° to W. by S. 



At the western end of the Mitan gcfrge we enter the coal field of Kwei. Here 

 the limestone disappears under strata, apparently conformable with it, of a fine- 

 grained micaceous sandstone, which, below Kwei, is succeeded by a fine-grained, 

 gray, calcareous sandstone. The trend of the beds which, near the gorge, was 

 N. N. E. with a dip of about 40° to W. N. W., changes here to N. Avith a dip to 

 E., and further up, opposite Kwei, it is N. by W. with an inclination of 70° to E. 

 by N. Here is the beginning of a series of those angular plications so common to 

 Coal measures in all countries. Small beds of limestone and red argillite alternate 

 with the sandstones until, about two miles above Kwei, the first coal seams crop 

 out, and with the appearance of these, the trend changes to N. W. by W., more 

 than 90° from its normal direction of N. E. S. "W. 



The seams of coal are of an inferior friable anthracite. Those I visited above 

 Kwei were highly inclined between sandstone walls, and contained, according to 

 the Chinamen, only six to eight inches of fuel. Capt. Blackiston, who took speci- 

 mens of these rocks and noticed, with much accuracy, the general features of this 

 region, remarks that the rocks of the coal regions of Sz'chuen, wherever he saw 

 them, presented the same appearance as those of the Kwei field.^ It would seem 

 probable that in Sz'chuen, which seems to be occupied by an immense coal basin, 

 the Coal measures exist with a much greater thickness than in the Kwei field, 

 where only the lower members seem to have been preserved. Deposits of iron ore 

 occur in intimate connection with coal and limestone ui Sz'chuen," and, as we shall 



' Five Months on the Upper Yangtse. ° Ibid. 



