262 



A. Mc Henry — Trachytic Rocks of Antrim. 



normal place between the clialk and basalt, it occurs in the form of 

 a loose gravelly clay. 



The trachyte in this locality is generally compact and fine-grained 

 in texture, light-grey and white in colour, sometimes mottled 

 pinkish; and on its weathered surface bears a close resemblance iu 

 colour to the underlying chalk, so much so, that a casual observer 

 might at first sight suppose the chalk and trachyte to form portions 

 of one rock-mass. The basalt is of the usual amygdaloidal character, 

 and weathers spheroidally. 



Fig. 2 shows the relative position of the rocks in the Avest end of 

 the quarry, and it is interesting to note how the trachyte behaves in 

 this instance. It has forced its way underneath the basalt along the 

 zone of the flint-gravel bed, which it carries on its back, and at one 

 l^lace portions of the gravel bed rest both above and below it. 



Fia:. 2. 



West end of Templepatrick Quarry, county Antrim. 

 C. Chalk. G. Flint-gravel bed. B. Lower Basalt. T. Trachyte. 



At Ballypalady, 1^ miles north-east of Templepatrick Quarry, 

 evidence exists to show that the trachytp is older than the Upper 

 Basaltic sheets, and at Libbert Bauxite Mine, near Glenarm, further 

 proofs on this point are to be found in the trachyte-conglomerate 

 and trachytic sands which occur between the Upper and Lower 

 Basalts. 



Fig. 3 is a section of the Ballypalady rocks which was, and is 

 still, I believe, to be seen in the old open workings of the pisolitic 

 iron-ore excavations. The bed of conglomerate contains rounded 

 and subangular lumps and finer debris of the Templepatrick variety 

 of trachyte, as well as fragments and detritus of the Lower Basalt, 

 the whole being capped by Upper Basaltic sheets. 



This is one of the localities from which beautiful plant impressions, 

 leaves, fir-cones, etc., were obtained. These have been figured and 

 described by the late Mr. W. H. Baily and Mr. J. Starkie Gardner. 



Fig. 4 is a section of the Libbert Mine. Glenarm, from which 

 a fine collection of plants, etc., was also obtained, when it was being 

 worked for Bauxite some twenty years ago. 



