But there is one point to which I must advert, which was brought prominently under our notice a short time ago by one of our members, in his account of the Cheshire Salt District, viz., that lakes may be due to a subsidence of ground, owing to materials having been taken away or dissolved from a distance under ground. There can no denial be given; the fact is an established one, and it only influences the position which I have taken up by showing that the depression which forms a mere may be made by underground as well as by the superficial solution of material. The geologist, in each case brought under his notice, may investigate which is the most probable cause; but the general philosopher can well afford to pass such minor points by.

I may mention also, ere I close this essay, that Mr. D. T. Ansted, in a Paper in the Cambridge Philosophical Transactions, vol. XI., entitled, "On some Phenomena of the weathering of Rocks," calls attention specially to the influence of heat in producing cracks or fissures; of frost in producing disintegration; and of vegetation in producing rounded holes, and dislodging masses of rock. It is quite unnecessary for me to enter into these matters fully, as they belong more to geology proper than to the observations of an ordinary traveller. But I may borrow from him a concluding sentence, which so thoroughly accords with my own feelings, that I prefer copying to paraphrasing it. It runs thus: "If, therefore, we would learn how, when, and why the hills exist as we see them; how the valleys were scooped out; how the mountain crests became jagged; why the undulated surface of one country is developed into vast prairies, while the smoothed plains in certain districts become flat steppes and sandy deserts; why the plateaux are rent across with broad deep fissures; and why the

appearance of sea cliffs is simulated in the interior of a country by long lines of escarpment; we must observe existing nature before theorising on its past history, and steadily direct our view to that which is, before we attempt to explain the distant and obscure outline of that which was."

THE MERSEY AS KNOWN TO THE ROMANS. BY JOSEPH BOULT, F.R.I.B.A., &c.

It is upwards of fifty years since Dr. Ormerod, in his valuable History of Cheshire, adduced presumptive evidence that in ancient times the upland waters of the Mersey flowed into the Dee, on their way to the ocean. Since then, I believe, little has been done to confirm or disprove this conjecture, yet it might be supposed to be of considerable interest in this locality, and well worthy of attention from Geologists and Topographers. In the course of my inquiries into the changes in the bed of the Mersey, I have gleaned a few facts which may help to illustrate this important conjecture; and after briefly stating the views of Dr. Ormerod, and some other writers, I will submit my own conjectures as to the facts.

Dr. Ormerod writes: "The boundaries of the Hundred of Wirral on two sides are formed by the two estuaries; on the third side by the waters of the Irish Sea; and on the fourth, they are defined by a deep valley running across in an irregular direction from the Mersey, by Stoke, Croughton, Chorlton, Backford, and the two Mollingtons to the Dee, separating Wirral from the Hundred of Broxton."

The Doctor then remarks: "It will here be necessary to overstep the limits of the Hundred, and to observe that the raised terrace formed by Wirral, between the waters of the two estuaries, after being broken by the deep valley beforementioned, continues its course onwards, in a S. E. direction, towards the feet of the Broxton Hills, still retaining on its sides two deep and broad vales, each of which is a continuation of the line of the respective estuaries. The vale on the

N. E. is traversed during its whole length by the waters of the Gowy. The vale on the S. W. forms in its upper part the bed of the Dee, which, however, instead of proceeding down the rest of the vale to the estuary in a straight line, is diverted to the walls of Chester by a deep channel, formed in the elevated line before-mentioned, which carries the water past Chester in a direction nearly semi-circular, till it joins the estuary and the line of the great vale again, near Blacon point. This channel is supposed to be in a great measure artificial, and is stated in some antient pleadings relative to the Dee Mills to have been made by Hugh Lupus. Harl. MSS., 2084, 157."

"That the waters, before the retiring of the sea from the western coast of Britain, occupied the line of these vales, will be doubted by no one who has looked down on the general level of the country, either from the forest hills, or from the ridge of the great natural terrace before-mentioned near Aldford or Churton. A tide, a very few yards higher than usual, would now cover them to a considerable extent.

"Having thus shown that vestiges exist, in the general face of the country, manifesting that the waters occupied a wider range than the present height of the tides allows, it remains to mention that a tide much lower than would suffice to cover these levels would fill the before-mentioned smaller valley which intervenes between Wirral and Broxton, and render the former Hundred a complete island, — as the country tradition still maintains it to have been at a distant period. The variation of level is indeed so inconsiderable that it was once proposed to take the Dee through this line into the Mersey, instead of pursuing its present artificial course by embankment; and it was in consequence of this suggestion that Mr. Pennant made a series of observations, which led to the connexion of the two rivers by the present canal." P. 187.

"At the point where this valley joins the Mersey, we have the township of Ince (Inys, or the island), a place which could only obtain its name by an elevation of the waters to the height supposed; and near the other end, but three miles farther from the sea than the termination of the valley in the Dee, as late as 31 Edward III., we find the abbot of St. Werburgh, in his plea to a quo warranto, claiming, among other manerial privileges, "Wrecum maris," in his manors of Broughton, Huntington, and Cheveley.

"As a last proof, whether the inferences drawn from these circumstances are correct, the soil has been examined in Chorlton, Coghull, and other parts of the valley; and about a yard below the surface it has been found to be uniformly composed of the same grey sea sand, as the ground which has been recovered from the Dee by embankments. A very considerable quantity of sea shells is also deposited in the gravel, which occasionally is found on the sides of the valley; and roads which have been covered with it appear plentifully bestrewed with sea shells and their fragments, after the surface has been washed by a shower.” *

The alleged deviation of the river Dee referred to above has been ascribed to the Romans, whilst it is asserted by others that the present bed of the Dee, in its course from Aldford to Chester, bears no mark of art; and the mounds of earth thrown up in the vicinity of the river are attributed to the rude warlike purposes of our ancestors.†

In a note to the observations already quoted, Dr. Ormerod says: "Some other points remain to be noticed. If the reader turns to any old map of Cheshire, he will find a stream carried through from river to river between Wirral and Broxton, in the line which is here supposed to have been an

Intro. Hund. Wirral., Hist. Ches. vol. ii., p. 187. The argument from the sand, shells, and gravel was withdrawn by Dr. Ormerod in 1854, vide Journal of the Archit., Archæol. and Hist. Society, Cheshire, part iv., p. 467.

+ Stranger in Chester, pp. 171-172.