and Chalk at Goodland Cliff and Torr Eskert. 1 85 



fragments had been rounded by attrition, and consequently that the chalk which surrounds them 

 is newer than the syenite. But it may be observed, that the syenite itself includes pebbles of quartz, 

 similar to those contained in the green sand and chalk. This fact, when coupled with the peculiarly 

 rounded and indented form of the upper surface of the syenite, and the smooth flattened one of the 

 lower, leads to the conclusion, that it was injected in a fused state into the chalk, when the latter 

 was soft or plastic ; and that it may be considered similar to the small reniform fragment of syenite 

 included in the chalk, as seen in specimen No. 10. If the chalk were not first formed, how can we 

 account for fragments of that substance being included in the syenite, as exhibited in the drawing 

 No. 4, and in specimens Nos. 10, 11, 12, 13 ; and above all, how can we account for the irregular 

 stratum of chalk, with green sand, &c., which occurs below the syenite, and interposed between 

 that rock and the mica slate, as exhibited in cuts Nos. 4 and 5 ? 



It may also be mentioned, that it is not unusual to find chalk intermixed with trap, and trap 

 entangled in chalk on the Antrim coast. Examples of both occur at Kenbane Head, west of Bally- 

 castle ; and in the section No. 1, appended to this paper, the southern extremity of the greenstone 

 of Fair Head, is shown penetrating the chalk, while the chalk itself includes masses of trap. 



It is perhaps unnecessary to dwell on this subject^ as it is hoped that the 

 drawingSj together with the specimens^ will sufficiently illustrate the relations 

 of the mica slate, chalk, and syenite : and if it appears, that the views now 

 put forward, have been substantiated, a new and important fact will have 

 been added to those, already described by other observers, which may ulti- 

 mately lead us to attribute a comparatively recent origin, not only to syenite 

 veins and to greenstones formerly called primary, but also to many other 

 crystalline rocks. 



I have long doubted the existence of true beds of the large grained cry- 

 stalline greenstone or granite, in schistose sedimentary rocks, being of opi- 

 nion that if carefully examined, they would, like the syenite now described, 

 prove to be intrusive veins, and not beds subordinate to those rocks ; but I 

 forbear entering further upon this subject at present. 



October, 1835. 



VOL. V. SECOND SERIES. 2 B 



