The Inundation of Leasowe

Robert Stevenson, the Scottish Lighthouse Engineer, first visited the Wirral Lighthouses in 1801, while he was still learning his trade, six years before he started construction on the Bell Rock Lighthouse.

Stevenson returned to Wirral in February of 1828 to carry out an investigation of the Cheshire shore, between the Mersey and the Dee, in the company of William Laird (the shipbuilder) and Sir John Tobin (former slaver, privateer and Mayor of Liverpool). Presumably his expertise was enlisted after the sea breached the bank at Leasowe on 16-18 February, and threatened to turn much of Wirral into a “permanent salt lake”. Stevenson promptly presented his findings to the Wernerian Society in Edinburgh on 8th March 1828. His account of these investigations touched upon the submerged forest of Meols, the loss of the original lower sea-light at Leasowe, and the general encroachment of the sea upon the land. Today, we would explain this encroachment in terms of rising sea levels caused by global warming, but terms like “climate change” and “global warming” were not part of Stevenson’s vocabulary.

The construction of a new embankment at Leasowe commenced in 1829.

Here is the full text of Stevenson’s 1828 paper, transcribed from the Edinburgh New Philosophical Journal.

Remarks upon the Wasting Effect of the Sea on the shore of Cheshire, between the rivers Mersey and Dee

By Robert Stevenson, Esq. Civil-Engineer, F.R.S.E., M.W.S., &c. Communicated by the Author.

On a former occasion, I had the honour to make a few observations, which appeared in the 2nd volume of the Society’s Memoirs, regarding the encroachment of the sea upon the land generally. The present notice refers only to that portion of the coast which lies between the rivers Mersey and Dee, extending to about seven miles. To this quarter my attention, with that of Mr Nimmo, Civil Engineer, had been professionally directed in the course of last month. In our perambulatory survey we were accompanied by Sir John Tobin, and William Laird, Esq. of Liverpool, along the Cheshire shore, and its connecting sand banks, between Wallasea Pool, in the Mersey, and Dalpool, in the river Dee. Within these estuaries, the shores may be described as abrupt, consisting of red clay and marl, containing many land or boulder stones, of the cubic contents of several tons, and very many of much smaller sizes, diminishing to coarse gravel. But the foreland, or northern shore, between these rivers, which I am now to notice, is chiefly low ground, and, to a great extent, is under the level of the highest tides. The beach, or ebb, extends from 300 to 400 yards seaward and, toward low-water-mark, exposes a section of red clay ; but, toward high water, it consists of bluish coloured marl, with peat or moss overlaid by sand. This beach, at about half-tide level, presents a curious and highly interesting spectacle of the remains of a submarine forest. The numerous roots of trees, which have not been washed away by the sea, or carried off by the neighbouring inhabitants for firewood, are in a very decayed state. The trees seem to have been cut off about two feet from the ground after the usual practice in felling timber, and the roots are seen ramifying from their respective stumps, in all directions, and dipping towards the clay subsoil. They seem to have varied in size from 18 inches to perhaps 30 inches in diameter, and, when cut with a knife, appear to be oak. Several of the boles or trunks have also been left upon the ground, and being partly immersed in the sand and clay, are now in such a decomposed state, that, when dug into with a common spade, great numbers of the shell-fish called Pholas candida, measuring about three-fourths of an inch in length, and two inches in breadth, were found apparently in a healthy state. These proofs of the former state of this ebb or shore, now upwards of 20 feet under full tide, having been once dry land to a considerable extent beyond the region of these large forest trees, were rendered still more evident by the occurrence of large masses of greenstone, which, at a former period, had been imbedded in the firm ground here, and especially on the shore within the river Dee. It may farther deserve notice, that the inhabitants of this district have a traditional rhyme, expressive of the former wooded state of this coast, where not a tree is now to be seen, viz. “From Halbre Isle to Birkenhead a squirrel may hop from tree to tree;” that is from the Dee to, the Mersey, now presenting a submarine forest.

As these evidences of great changes upon the state and former appearances of the land were highly interesting to the party, and intimately connected with the professional inquiries of myself and colleague, it seemed desirable to get them, if possible, corroborated by oral testimony. Sir John Tobin accordingly, very obligingly, took measures for examining the oldest people in the neighbourhood, as to their recollection of the former state of these shores. In particular, Thomas Barclay, aged 93 “all but two months”, by profession a mason and measurer of country work; Henry Youd, labourer, aged 86; and John Crooksan, labourer, aged 80, were examined. Barclay stated, that he had been employed at the erection of the Leasowe landward Lighthouse in the year 1764; that there were then two lighthouses near the shore, for a leading direction to shipping through the proper channel to Liverpool ; and that the Sea Light became uninhabitable, from its being surrounded by the sea. A new light was then built upon Bidstone Hill; and the present Leasowe Lighthouse, formerly the landward light, which he had assisted in building, became the sea-light. He could not condescend upon the distance between the two original lights, but was certain that it must have been several hundred yards; that he knows that, in the course of thirty years, the shore of the Leasowe lost, by measurement, eleven Cheshire roods, or 88 yards; and verily believes, that, since he knew this shore, it has lost upwards of half-a-mile of firm ground. To the correctness of these statements, the other two aged men gave ample testimony; Henry Youd having also worked at the Lighthouse.

As to the present state of things, the party alluded to were eye witnesses of the tides, on the 16th, 17th and 18th of February 1828, having exhibited a very alarming example of the encroachments of the sea upon the Leasowe shore. At high-water it came over the bank, and ran in a stream of about half-a-mile in breadth, surrounded the lighthouse, and continued its course through the low grounds toward Wallasea Pool, on the Mersey, thereby forming a new channel, and threatening to lay several thousands of acres of rich arable and pasture lands into the state of a permanent salt lake. The present Leasowe Lighthouse, which, in 1764, was considered far above the reach of the sea, upon the 17th of February last was thus surrounded by salt water, and must soon be abandoned unless some very extensive works be undertaken for the defence of the beach, the whole of the interior lands of the Leasowe being considerably under the level of high-water of spring-tides.

This coast, with its sand banks in the offing; its submarine forest, and the evidence of living witnesses as to the encroachment of the sea upon the firm ground, is altogether highly interesting to the geological and scientific enquirer. The remains of forests in the bed of the ocean occur in several parts of the British coast; particularly off Lincoln; on the banks of the Tay, near Flisk; at Skiel, in the Mainland of Orkney, and in other places, noticed in the Transactions of this Society, and are strong proofs of the encroachment of the sea upon the land. However difficult, therefore, it may be to reconcile the varied appearances in nature, regarding the sea having at one time occupied a higher level than at present, yet its encroachment as a general, and almost universal principle, seems to be beyond doubt in the present day. Since I had last the honour of addressing the Society on this subject, opportunities have been afforded me of making many additional observations on the British shores; and of personally extending these to almost every port on the Continent, between the Texel and the Garonne. I have also through the obliging communications of friends, been enabled to extend my inquiries to other quarters of the globe; and I am now prepared to state, that, with a few comparatively trifling exceptions, the sea appears to be universally gaining upon the land, tending to confirm the theory, That debris, arising from the general degradation of the land, being deposited in the bed of the minor seas, is the cause of their present tendency to overflow their banks.

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