YENANGYOUNG. 8r 



there is a good deal of Assuring, particularly towards Beme, but the- 

 fissures intersect the strata without, in most instances, producing 

 faulting. The diagram and plates exhibit numerous instances of 

 a series of beds being intersected by a fissure, without otherwise 

 being disturbed by it. Diagram fig. 7 affords a very good instance 

 of a vein (a) which traverses a succession of beds at a very hi°h 

 angle, without producing any dislocation. 



These veins are mostly filled by either gypsum or fine mud 

 between which there is probably some genetic connection. 



The gypsum veins are filled with an argillaceous gypsum, 

 arranged in layers, parallel to the walls of the vein, and of darkish 

 brown colour. They are generally very hard and stand out in the 

 form of a reef from the surrounding softer strata. So far they afford 

 no particular interest, while the mud veins possess a great theoreti- 

 cal interest. 



My attention was first roused by the peculiar appearance of cer- 

 tain beds of clay imbedded in the regular sequence of the series at 

 the northern part of the oil field. The clay did not exhibit any sicrns 

 of being stratified, nor was it homogeneous ; it consisted of a mass of 

 fragments of clay, which apparently were removed from some other 

 beds, mixed with a few hard concretions; the whole mass was 

 apparently horizontally spread out. At first I felt inclined to interpret 

 it as a bed of clay pebbles such as may frequently be observed where 

 a tenacious clay is exposed to the action of waves. When surveying 

 the southern part of the oil field, however, the true explanation was 

 at once found; these beds represent nothing else but true eruptive 

 mud. Before discussing these horizontal beds of eruptive mud, it wiFl 

 be useful to examine and describe those sections which exhibit 

 the best instances of eruptive mud in veins. 



As already mentioned, the finest instances can be seen in the 



southern part, particularly along the Taungle ravine, which is nearly 



everywhere intersected by mud veins. The best section is figured 



on plate VIII, and part of it has been enlarged and reproduced in. 



G ( 127 ) 



