Associated Hocks South of Wexford. 497 



" schists " he calls "argillites," and he supposes they are the saoie 

 as the " submetaraorphic rocks " north of the dyke ; but as he 

 himself describes his " argillites " as '• principally talcose and horn- 

 blendic," it is obvious that they cannot be identical with the slates 

 of the " submetaraorphic " series, which, though sometimes slightly 

 talcose (or chloritic), are never homblendic. 



" Lower Silurian " Zone. — This band (b 2) occupies the country 

 between the metaniorphic zone, and the Carboniferous band south 

 of Wexford. From Mr. Kinahan's later works, I understand he has 

 modified his original opinion, and has adopted a Cambrian age for 

 the rocks. I believe it will be found that four distinct formations 

 are represented within the area. 



(1) Ordovician. — Grey shale, grit, and conglomerate, near Tagoat, 

 with OrtJiis Actonice and 0. testudinaria. Black and grey shales at 

 Bannow. These, the ordinary types of the district, show their 

 affinity with the Bala series, not only in their fossils, but by their 

 close lithological resemblance. 



(2) Cambrian {Longmynd). — The prevailing types are pale-green, 

 red, and purple clay-slates. They are well seen on the shore at 

 Bannow, and are said to contain Oldhamia. They are true argilla- 

 ceous deposits, and are easily distinguishable from the felspathic 

 slates of the " submetamorphic " group. Considering the great dis- 

 tance between the two areas, their resemblance to the Salopian types 

 is very striking. In an examination of the localities where they are 

 said to pass into " submetamorphic " rocks, I failed to find the slight- 

 est foundation for such a conclusion. The Cambrian is as unaltered 

 as in the Longmynd Hills, while the felspathic series usually exhibits 

 a slight glaze indicative of incipient metamorphism, and sometimes 

 contains beds of hornstone. 



(3) Hypometamorphic series. — As these rocks are everywhere 

 faulted against other formations, petrology furnishes us with no 

 proof of their age. They are quite unlike Ordovician and Cambrian, 

 both in mineral characters and state of alteration. At the same time, 

 their resemblance in both points to the Pebidian rocks of Anglesey 

 is very marked. It is difficult to present the full force of this argu- 

 ment on paper, but after several months' close study of the Welsh 

 types, my examination of the Wexford rocks produced a very strong 

 opinion of the identity of the two series. The prevailing rock in 

 both areas is the pale-green altered felspathic slate. Similar grits 

 and hornstones also occur. Bands of quartzite, which are not usual 

 in Pebidian rocks in England and South Wales, are found in 

 Anglesey, and more conspicuously in the Wexford district. Any 

 inference from the strong lithological affinities here indicated could 

 not, of course, withstand clear stratigraphical evidence, but, as such 

 proof is wanting, lithology aifords a high probability of contempo- 

 raneity. 



(4) Iletamorphic series. — Here also petrology is of little service, 

 and lithology is again almost the only available guide. Comparing 

 these rocks with our known gneissic formations, the Lewisian and 

 the Anglesey group, presumably Dimetian, the resemblance to the 



DECADE II. VOL. VIII. — NO. XI, 32 



