parently made earth on their brows" (p. 66).

Of course; and this

"made earth," or, in other words, silt and soil, with land shells, fine gravel and small stones, loosened by the plough from the surfaceslope above, and washed down by the rains until some hedge, or wall, or even less trifling boundary, more or less horizontal, checked the downward wash of surface matter, will be found, if I mistake not, to form the substance of all these terraces and banks-except where some harder stratum crops out from the hill-side, and gives a support to the arable terrace above.

FIG. 4.-TERRACES NEAR LLANGOLLEN, AS SEEN FROM THE HILL NORTH OF LLANTYSILIO RAILWAY STATION.

No one, of course, disputes the existence of true sea-cliffs and escarpments, or of raised sea-beaches on some of the coast-lines of our island, or that some of the latter may penetrate its estuaries, and be found at considerable heights above the present tidal level. Where sufficient evidence of these latter facts is produced, they are, and will be, readily accepted by all geologists. It is to the innumerable minor banks and terraces (popularly called balks and lynchets) which Mr. Mackintosh truly describes as scoring the sides and reaching to the summits of many inland hills in the Cretaceous and Oolitic, and other formations of our island, that my remarks refer. These, I believe, to be of artificial origin,-to be owing to the disturbing action of the plough and the mattock on the surfaceslopes, aided by downward rain-carriage of the loosened soil-a process which is visibly going on wherever a hill-side is under cultivation. And I look on Mr. Mackintosh's notion of their being "raised sea-beaches" as a preposterous theory without a shadow of foundation.

On the whole, it is evident that before Mr. Mackintosh can be accepted as a reliable authority by his readers on the "Causes of Denudation, and the origin of Natural Scenery throughout England and the World," he must unlearn many of his present notions upon the "very limited power of atmospheric," and the almost exclusive agency of "marine denudation," in shaping the surface of our continents, which compose the substance of his recent volume. If as a lecturer he repeats this theory of denudation to an agricultural audience in the southern

counties, he will be liable to some such muttered interruption from an incredulous old farmer, as that of Edie Ochiltree to the Antiquary's far-fetched assertions-" Sea-beach here, sea-beach there; I mind the bigging of 'em."

IV. ON THE MIDDLE PLEISTOCENE DEPOSITS.

By Professor HARKNESS, F.R.S., F.G.S.

HE superficial deposits of the Co. of Wexford, containing a

THE rich marine fauna, have been referred to in Professor E.

Forbes's Memoir on "The Geological Relations of the existing Fauna and Flora of the British Isles."1

In an appendix to this memoir the several shells which have been obtained from the superficial deposits of this portion of Ireland are mentioned. A list of the fossil contents of these deposits had been previously given by Sir Henry James, who first pointed out the occurrence of these shell-bearing strata in the Journal of the Dublin Geological Society, Vol. III. The fossils mentioned in this list have been also determined by Professor E. Forbes.

The strata affording these fossil shells are described by Sir Henry James as very extensively developed in the Co. of Wexford, and occupying an area forty miles in length, by from eight to nine miles in breadth. They consist of sands and gravel and drift, and repose upon rounded pebbles." On the sides of the Firth Mountain they attain an elevation of 400 feet above the level of the sea. Their thickness near Blackwater is said to be 174 feet, and their base is nowhere seen.

On four of the sheets of the Geological Survey Maps of this part of Ireland (sheets 47 S.E., 47 N.E., 41 S.E., and 41 N.E.), these strata are referred to as follows:- "The low lands of this coast and the interior up to a height of between two and three hundred feet are covered by Pleistocene deposits, consisting of marls interstratified with sand and gravel, containing Arctic and other shells, chalk-flints, pebbles of Antrim chalk, jasper, coal, etc., and magnetic iron sand." Many of the species of shells which occur in these beds are in the Museum of the Geological Survey of Ireland, and the several localities from whence the specimens have been obtained are recorded on the underside of the slabs upon which they are mounted. By the kind assistance of Mr. Baily, Paleontologist to the Irish Survey, I have been able to give the following as localities from whence these specimens have been derived :-Ballyteige, Killiley, Rathaspick, Castle Ellis, Killisk, Ballyhuskard, Artramon, Ballyvaldon, Ballyknockan, Killmackridge, St. Margaret's, Killinkorley Clonmure.

The portion of the Co. of Wexford where these superficial deposits occur is marked by a circumstance which at once recalls, to the minds of those who have seen them, the Boulder-clays of Lancashire and Cheshire, and their associated strata. Great numbers of pits are seen scattered over the parts of Wexford where the superficial 1 Memoirs of the Geological Survey, Vol. I.

deposits are formed; but by far the greater portion of these have been abandoned for many years, and are now full of water. From these pits have been derived materials used in the improvement of the land, and in every respect they are analogous to the marl pits in the English counties above alluded to. There are now very few dry pits in the northern portion of the area occupied by the superficial deposits in the Co. of Wexford; and those in the southern portion of the county afford very little evidence concerning the relative position of the strata which they exhibit.

Sir Henry James has stated that the base of the superficial deposits in this part of Ireland is not seen; and to this might be added, that for the most part we have little information as to the strata which are newer than the shell-bearing sands and gravels of the Co. of Wexford. There are, however, a few localities where strata of a different nature, and with well-pronounced features, are seen resting upon the shell-bearing deposits.

One of these localities is in Castle Ellis, about a quarter-of-a-mile north of the Post Office, in a field on the east side of the high road. Here there are two dry pits, one of which has recently been worked for material for the land. The sides of this pit exhibit a mass of reddish-brown Boulder-clay, about forty feet in thickness. This clay rests upon sandy and gravelly strata in some instances, almost consolidated by the infiltration of carbonate of lime. These sands and gravels forming the lower beds of the pit, are only exposed to the depth of about twelve feet.

The Boulder-clay above them abounds in angular, subangular, and rounded blocks of rocks, derived principally from the Cambrian and Silurian formations; and, in many instances, these blocks are beautifully striated.

Some of the sandy layers are very strongly impregnated with small particles of shells; and it is from these layers that the materials which are used for the improvement of land are obtained.

In Castle Ellis, on the same side of the road, a short distance south of the Post-office, there is another large dry pit, the upper portion of which also consists of Boulder-clay. Here, however, the Boulder-clay is not more than twelve feet in thickness, and the rest of the pit, which is of considerable depth, is made up of sands and gravels. A little further to the south, on the opposite side of the road, another dry pit occurs. The latter consists of sands and gravels exclusively, the Boulder-clay having thinned off before reaching this spot. The sands and gravels in the last mentioned pit are now largely worked, and, in common with the same deposits in other parts of the Co. of Wexford, they are known as "Manure gravels." It is to the abundance of fragments of shells, which occur in these deposits, that they owe their value for agricultural purposes.

Some other spots on the road from Castle Ellis to Wexford afford also "Manure gravels." One of these is at Pulregan, near Castlebridge. Here, and in several other localities, the "Manure gravel" deposits exhibit a rounded outline, having much of the contour of Eskers. At Pulregan, besides numerous fragments of bivalve shells,

i umi a je gravels some of which are in a perfect

of Wexford, and to the south

1783 make their appearance; but here, as elsedepose are not seen, and here they

* De Tens í steis later bed by the late Prof. E. Forbes from Les gu' The Word forty-three are common 31 mas 18 vi s Fu ists datizous, the variety contrae secimens in the collection of the LA SERT The specimens of this form, collected by astle Els were of the crinary variety and of small

I de gels fom the Manure gravels" are forms Wir ver a de artem British Seas; seven appertain to 3 Anri de cast of Greenland; and four are now amin ss scra of the Frise Isles. Taking the whole of the dria Der pter 2 minute a temperature somewhat colder than a the present ses of the Wexford coast, but by

Resas sura a my pustimate as is represented by the shells When late teen damel from the deposits of Scotland and elsemem din sag nan the Baller-clays

The as surence & Folder-clays store the shell-bearing sands and pans the Qa of Weird Wool at first sight, induce the conAINUL DE DERE ST appertain to a horizon nearly allied to that of 20 Never Lang: and this inference is, to some extent, prevalent

ZAKETE RNsy to lock for their equivalents elsewhere, mi v se de colores under which those equivalents present sites bed ang at any conclusion as to the age and postora zë She – Veme garelis” There are two features in con1917 de "Mizure gravels" of the Co. of Wexford which 129 higher characteristic of them: one is, the presence of shells, and fagnens of shells, which distinguishes them from Eskers, to which mer an perly clad in arrangement and in the general nature of their waxas; the other feature which marks them is the constant ormance in them of fint pebbles, which are almost altogether

sowent from the Eskers

There are several localities in Ireland where beds, having the same nature and aftring precisely the same contents as the Me gavels" of the Co. Wexford, are to be found.

One of these localities is the north side of the headland of Howth, the northern bendary of Dublin Bay. The strata, which are here well seen near the village of Howili, have been described many years ago by Dr. Scouler. They consist of sands and gravels, the latter being limestone fragments, with which are associated flint pebbles. The section is about 200 feet in thickness; and Dr. Scouler states that the beds afford Turritella terebra, Turbo littoreus, Nerita hattoralis. buccinum undatum, Cardium edule, Cyprina Islandica

Pecten varius, and Dentalium entale, generally in a fragmentary 1 Dublin Geological Journal, Vol. I., p. 270.

con

dition. These shell-bearing beds, with flint pebbles, rest upon a mass of Boulder-clay containing abundance of striated blocks, well seen at Balscaddan Bay; and this Boulder-clay reposes immediately upon the Carboniferous limestone.

The position of the shell-bearing beds, with flint pebbles, at Howth, resting on Boulder-clay, would at first sight appear to indicate a different and a higher horizon for these strata than for beds having the same nature in the Co. of Wexford, since the latter have Boulderclay above them.

It must, however, be remembered that, in the Wexford area, the strata upon which the "Manure gravels" rest are not seen.

On following the gravels and sands of Howth, eastwards, they are found to be covered by Boulder-clay, which does not exceed more than three feet in thickness; and this Boulder-clay most probably represents the lower portion of the similar deposits which, in Castle Ellis, in the Co. of Wexford, covers the "Manure gravels."

Subsequently to the observations of Dr. Scouler on the shelly gravels and sands of Howth, Dr. Oldham has described beds of the same nature which occur in other parts of Ireland.' He also notices the appearance of flint pebbles in these strata; and he adds to Dr. Scouler's list of shells the following species:-Ostrea edulis, from Killiney and Bray; Tellina solidula, not uncommon; Pecten opercularis, from Killiney; Pullastra decussata, from Killiney and Bray; Nucula oblonga, Astarte Gairensis, from Killiney, Bray, and Sugarloaf; Nucula nucleus? and Saxicava rugosa, rare. Further observations in these beds also induced him to add to his previous list the following forms as occurring near Dublin:-Rostellaria pespelicani, Fusus antiquus, Buccinum undatum, Nassa incrassata, Natica Alderi, Littorina neritoides, Trochus umbilicatus, T. ziziphinus, Triquetra species of Spirobis sp., Balanus (impressions of).

Since the observations of Dr. Oldham were made on these deposits, as they are seen in the districts around Dublin, they have attracted the notice of the Rev. Maxwell Close, who has paid special attention to the Glacial phenomena of Ireland. The Rev. Mr. Close has recognized the occurrence of the shell-bearing sands and gravels in the high ground to the south of Carrickmine's station, on the Dublin and Bray railway.

Here flint pebbles also make their appearance, and shelly fragments, the most abundant being portions of Cyprina Islandica.

The Rev. Mr. Close has also detected these shelly sands and gravels on the south side of the Three Rock Mountain, at an elevation of about 1,200 feet above the sea level.

The several species of mollusca, which have been obtained from the sands and gravels in the neighbourhood of Dublin, are such as are most common in the "Manure gravels" of the Co. of Wexford; and, like them, they do not indicate Arctic conditions in the seas in which they lived.

Sands and gravels of a nature similar to those of the neighbourhood of Dublin and the Co. of Wexford, have been found in other 1 Op. Cit., suprà, Vol. III., p. 61. 2 Op. Cit. suprà, Vol. III., p. 131.

VOL. VI.-NO. LXVI.

35