THE GEOLOGIST. 



TFTE LrnvER Ludlow Rocks. — Deaii Sie, — I see I have been called to 

 fifC'oinil, ill more tlifiii one page of jour February number, for errors of omission 

 and oiimiissioii; and in acknowledging the paternal rebuke, lam bound to be- 

 coiuea contributor j^ro tanto this month, 



First tlien, with regard to Major Austin's communication, which, in its latter 

 and more important part, gives us a fact of very high interest, viz., the occur- 

 rence of man in a true raised beach ! 



I believe his notice of the small patch of fossiliferous strata on the Water- 

 ford coast is quite correct, and that the strata of Newtown Head, opposite his 

 old station at Duncannon, are really of Llandeilo age. But the statement in 

 " Siiuria" is also true, viz., that all or nearly all* the Silurians of the south- 

 cast portion of Ireland are referable to the Caradoc rocks. It is a wonderfully 

 covered-up country : those who have not ridden across the drift-surfaces whicifi 

 clothe these denuded Silurian tracts can have little idea of the difficulty of 

 getting continuous sections. Hence it is impossible to say with accuracy that 

 we may not find anything or everything Silurian there. But after the best 

 attention that could be given to the whole tract, the govermnent surveyors 

 cannot determine any true equivalents of either the lowest or the succeeding 

 Silurian beds. Prof. Jukes has shown that there are no Lingula flags deter- 

 minable, and I must be responsible for saying that over the greater portion, at 

 least, of this wide district of Wexford and Waterford there is no proof of any- 

 tliing that can be called Llandeilo-rock, unless it be in the locality under con- 

 sideration. It is remarkable it should be thus. The Silurian strata are highly 

 contorted, cleaved, and interstratified with abundance of igneous rocks ; as 

 nnicli so in parts as the Llandedo-flag range of Cader Idris, or the wild country 

 round tlie vale of Ffestiniog. But the Irish . traps interstratified with fossil- 

 bearing slates are chiefly of the a.ge of those of Snowdon, and these belong to 

 the overlying series — the Caradoc or Bala rocks, as was shown clearly by Prof. 

 Ilamsay in his published sections. Now it so happens that one of the New- 

 town Heads in Waterford (that near Framore) is an excellent example of the 

 Caradoc strata, and is rather a conspicuous locality for fossils, many of which 

 Avere published in General Portlock's work. The other Newtown Head, from 

 wliich Mr. Austin gathered his rare organisms (sent to General, then Lieutenant- 

 colonel Portlock) is immediately opposite Duncannon, but on the Waterford 

 side of the estuary. It is rather a matter of satisfaction to me to find tliat 

 tiie sets of fossils are from distinct localities, for certainly the large species of 

 trilobite, Oxygia Portlocki and the others A)jipi/.v\ and Acidaspis, found by 

 Major Austin in his own locality are good Llandeilo types, at least they are 

 sucli as we may find in other Llandeilo-flag districts, such as Builtli, in Rad- 

 n()rshire. But tliough Caradoc is clearly superposed upon Llandeilo-flags, the 

 difference between the faunas of the two formations is not so great or decided 

 as j-o enable aiiYonc; at a glance to separate them ; and there are other districts 

 even in Ireland wliere perhaps the same distinctions may hereafter be drawn, 

 i)ul of whirli our knowledge is not perfect enough to enable us to do so at 

 ])r('S(Mi1. All the 1_v))ical Lower Silurian districts of Ireland, let me say mean- 

 while, are ol" th(^ Caradoe or Bala type, not even of Llandeilo age. I allude to 

 the Portrane distriel^ lUMr Dublin, the Tyrone, and probablv the Fermanagh 

 tracts, and. as before said, by far the greater part of Wexford, if not of Wick- 

 low. In Galway M (> ha\ e middle Silurian rocks ; in the picturesque Dingle 

 promontory, the AVenlock and Ludlow beds; and what may be revealed when 



• Thp st.rnlfl. near Waterford arc speciaUj- excepted as probablj^ of Llandeilo 'age (p. 1S5, 

 211(1 odu .). I do not know on what data. 



t Ciljimoir (hif)lic,if,i is nieniionod by Mr. Austin: I have onlv seen C. brevicapifafa from 

 l.ho sout h of livliind. 



