4i6 



NATURE 



\Atigust 15, 1878 



counties, however, as for instance Fermanagh and Sligo, it 

 assumes its more mountainous character. Nearly the whole of 

 this central plain is overlain with boulder clay, limestone gravel, 

 or middle drift, and extensive bogs, so that the subjacent rock is 

 but occasionally seen. In several places detached bosses of old 

 red sandstone rise through the limestone, and there is also good 

 reason for believing, with Prof. Hull, that the whole of the area 

 was at one time covered with the upper members of the carboni- 

 ferous group, including the true coal measures, of which un- 

 fortunately but small patches remain, and those upon the margin 

 of the plain. From the absence of the upper palDeozoic, 

 mesozoic, and cainozoic formations over the area, Prof. Hull has 

 arrived at the conclusion that the surface remained in the condition 

 of dry land, while that of England was being submerged beneath 

 the waters of the sea, over the bed of which nearly all these forma- 

 tions were deposited. To a certain extent, however, he leaves 

 it an open question whether some of the mesozoic strata which 

 occur over the north-east of Ireland may not have been deposited 

 over the centre and south. The amount of denudation over this 

 central area has, no doubt, been such that the chances of even 

 Prof. Judd finding traces of these later deposits appear at first 

 sight to be but small; but whether the whole of this vast 

 amount of denudation is due to the wasting influence of rain, 

 rivers, and other sub-aerial agents of erosion, is a question 

 which I venture to regard as at all events open to discussion. It 

 appears to be the case that in some parts of the north of Ireland 

 the whole of the upper carboniferous beds had been denuded 

 before the deposition of any permian strata, as these are de- 

 posited immediately on the carboniferous limestone ; and if this 

 amount of denudation had taken place in pre-permian times in 

 the north, there seems a possibility of the same having been the 

 case in central Ireland. If so, it is possible that some traces of 

 the later deposits may yet be found on the central plain. Cer- 

 tainly, if we are still to regard the white chalk as a deep-sea 

 deposit, the cretaceous rocks of the north-east of Ireland must 

 have at one time extended farther south than they do at present, 

 and somewhere or other there must have been shore deposits of 

 that period formed farther south than the Upper Greensand of 

 Antrim. The careful investigations of Prof. Judd have largely 

 extended our knowledge of the secondary rocks of the western 

 coast and islands of Scotland, and he has been able to show that 

 the Jurassic series of the Western Highlands could not have had 

 a thickness of less than three thousand feet. It is therefore hard 

 to believe that with such a development in so closely neighbour- 

 ing a district, the deposits of the same age in Ireland can have 

 been restricted to their present area. 



Prof. Judd considers that the amount of denudation in the 

 Scottish Highlands since the mesozoic, and even the miocene 

 period, has been enormous, and that the great surface features 

 of the Highlands were produced in pliocene times. It seems 

 therefore possible, if not probable, that so long a period of 

 exposure to sub-aerial influence as that assigned to the central 

 plain of Ireland by Prof. Hull would have resulted in a more 

 uneven land surface than that which we now find. At all events, 

 the history of this remarkable physical feature is one which is of 

 high interest, and can hardly as yet be considered as closed. 



With regard to the mountainous districts surrounding the 

 central plain, we shall, I believe, have the opportunity of visit- 

 ing some parts of the Wicklow Mountains, a district from which 

 a portion, at all events, of the native gold of Ireland was pro- 

 cured in ancient times, as indeed it continues to be. Of the 

 abundance of gold in this country in early times, a glance at the 

 magnificent collection of ancient ornaments preserved in the 

 museum of the Royal Irish Academy will serve to give an idea. 

 Even in times more recent than those in which the bulk of these 

 ornaments were made, gold was an important product of this 

 country, and I am tempted to quote a few lines from an early 

 English poem, " The Libell of Englishe Policye," written in the 

 year 1436. In treating of the commodities of Ireland, the 

 author says that the country is 



' ' So large, so gode, and so commodious, 

 That to declare is straunge and merveilous. 

 For of silver and gold there is the ore 

 Among the wilde Irish, though they be pore ; 

 For theyar rude and can thereon no skille, 

 So that, if we hadde ther pese and good wille, 

 To niine and fine and metal for to pure 

 In wilde Irishe mighte we find the cure; 

 — As in Londone saith a jewellere 



Which broughte from thennes gold oor to us here, 



Wherof was fined metal gode and clene. 



That at the touch no better coud be sene." " 



Sir William Wilde has observed that the south-western half 

 of Ireland has yielded a greater amount of gold antiquities than 

 the north-western, and probably this would hold good with 

 regard to the production of the metal itself, though it has beea 

 found in the counties of Antrim, Tyrone, and Derry, as well as 

 in those of Dublin, Wicklow, Wexford, and Kildare. 



The north-east of Ireland possesses, however, another geo- 

 logical feature peculiar to itself in that great expanse of volcanic 

 beds which formed the subject of Professor Hull's address to 

 this section at the Belfast meeting. My only object in now 

 mentioning them is again to call attention to their containing the 

 only remains of a miocene flora which are to be found in this 

 island. Analogous beds were detected in the corresponding 

 basalts in the Island of Mull by the Duke of Argyll in 185 1. 

 With the exception of the Hempstead beds of the Isle of Wight, 

 which should probably be classed as oligocene, and the Bovey 

 Tracey beds of Devonshire, these are almost the only deposits 

 of miocene age in the British Isles. The contrast presented by 

 the scarcity of deposits of this period in Britain with their 

 abundance in the north-west, centre, and south of France, 

 Switzerland, and generally in the south of Europe, is striking. 

 Instead of thick deposits covering hundreds of square miles of 

 country, like the miocene beds bordering the Pyrenees or those 

 of the great system of the Auvergne, M'e have small patches 

 owing their preservation either to volcanic outbursts having 

 covered them up, or to some favourable circumstance having 

 preserved them from total denudation. Whether we are to 

 assume with the late Prof. Edward Forbes, that the general 

 dearth of these strata in the British Isles arose from the extent 

 of dry land which prevailed during the long interval between the 

 eocene and pliocene periods, or whether we assume the former 

 existence of widespread marine deposits which have since been 

 entirely removed, the case is not one without difficulty. At all 

 events, the absence of representatives of this period within the 

 British area has a tendency to prevent a due appreciation of the 

 enormous extent of the miocene period being generally felt in 

 this country. Nor, generally speaking, do we, I think, take a 

 fair estimate of the remoteness in time to which we must date 

 back the commencement of that lengthened period. Prof. 

 Haughton, judging from the maximum observed thickness of 

 each successive deposit, has calculated that a greater interval of 

 time now separates us from the miocene period than that which 

 M-as occupied in producing all the secondary and tertiary strata 

 from the triassic to the miocene epoch, and, without endorsing 

 the whole of my accomplished friend's conclusions, I incline to 

 concur in such an estimate. When it is considered that the 

 Ballypalidy beds of Antrim and the Lough Neagh clays are 

 the sole representatives in Ireland of two periods of such length 

 and importance as the miocene and pliocene, their high interest 

 will be more apparent, and I trust that no opportunity of minutely 

 studying them will be neglected. 



There is one other point with regard to Irish geology on 

 which it will be well to say a few words, though it is of a nega- 

 tive rather than a positive character. I mean the absence, so 

 far as at present known, of palaeolithic implements in this 

 country. It is true that Prof. Hull, in the book to which I 

 am so much indebted, speaks of a raised beach on the Antrim 

 coast as containing worked flints of that rude form and finish 

 known as palaeolithic ; but this is a slip of the pen, by which the 

 author has fallen into the not uncommon error of applying a 

 term which is merely significant of the age of the implements to 

 their external character. However rude may be the workman- 

 ship of the flint implements found at Kilroot, they belong to 

 the neolithic, and not to the palaeolithic period. So far as I 

 am aware no example of any implement belonging to the age of 

 the mammoth, rhinoceros, and other members of the quaternary 

 fauna has as yet been foiyid in Ireland. Indeed, the remains of 

 Elephas primigenius and its associates are of exceedingly rare 

 occurrence in this country, though they have been found with 

 those of bear and reindeer in the Shandon Cave near Dungarvan. 

 It is, of course, impossible to foretell what future researches may 

 bring to light ; but judging from analogy it seems hardly pro- 

 bable that until ancient river-gravels containing the remains of 

 the quaternary group of mammals are found in this island, 

 veritable palaeolithic instruments will be discovered. The asso- 

 ciation of the two classes of remains is so constant that we may 

 fairly assume that the animals formed the principal food of the 

 palaeolithic hunters, and that any causes which lead to the absence 

 of the one class will lead to the absence of the other also. 



There, is, however, one member of that old quaternary group 



