Dundee Bridge. Dundee Courier, Wednesday 08 December 1869, p.2 col.5-6 (pdf image)
(Letter written Dec 4 1869, published Dec 8 1869)
Matthew warns, once again, that the proposed bridge might affect the “scour” of the Tay Firth, and block up the entrance to Dundee harbour. He questions, once again, whether the proposed scheme is “rationally practicable, within a paying cost, safe and necessary”, and he refers once again to his alternative bridge scheme at Newburgh.
Matthew also refers to a “near relation of the writer”, who more than a century ago constructed a series of stone walls to prevent further erosion of the Carse of Gowrie, under the direction of “Mr Crawford, proprietor of Errol”. It’s unclear who this “near relation” was.
[Want of space compelled us to leave over the following letter yesterday :—]
Sir,— There nothing I desire more than the prosperity of Dundee, and with very good reason, having land in the neighbourhood especially cultivated for the supply of Dundee. At the same time nothing is more gratifying to the lover of progress than the recent great rise of Dundee in certain kinds of textile manufacture. Having attained a superiority in these branches of honest industry and an abundance of capital, she is now in a condition to continue to take the lead in adopting every new improvement in quality of article and facility of production. It is under these propitious circumstances that the idea has arisen of bridging over the Firth at Dundee. No one could object to this, provided such was rationally practicable, within a paying cost, safe and necessary, that is, provided a much superior position for a bridge did not exist twelve miles up the Firth at Newburgh — the natural position where the Firth contracts into a river — affording quite as great or superior advantages to Dundee, while at the same time, it partook of none of the disadvantages, and could be carried out at one-third the cost. Acquainted with the locality, I pointed all this out, even before the construction of the Dundee and Perth railway — as the best line of rail for the East of Scotland, taking Dundee in its course, and also the best for the East and West crossing of Scotland from Dundee to Glasgow.
The great deposit of sand at the mouth of Tay Firth, extending westward from Barry to Broughty and southward to St Andrews, consists partly of the scouring of highland and upland water courses of the basin of the Tay, and partly of the abrasion of the Red-head Cliffs, which, in every north-eastern gale, are ground down by tens of thousands of battering rams, hard stone boulders, which every wave lifts up and dashes against the base of the red sandstone cliffs at the sea level. These links or dunes had been formed during a higher sea level, at least 25 feet above the present level, under cover of a bar on the eastern side of this sedimentary or drift formation. The Carse of Gowrie itself — a mud clay formation — as well as the clay deposit between Tayport and Leuchars owe their existence to this higher sea-level and raised wave bar at the mouth of Tay. Here the clay deposit has taken place in quiet water most inland, and the sand deposit where the sea wave has swept over, and where the wind has aided to raise the accumulation.
As the sea level became lowered some 25 feet in proportion to the land, the Tay and Earn rivers dug a channel for themselves through the lacustrine deposit of Gowrie Carse and Barry Sands. At first the channel was narrow and shallow, but in the course of time the channel became widened westward from Dundee to several miles of firth. Every winter a breadth of a number yards of the clay Carse was undermined by the waves which rose in time of storms on the Firth, and the clay mixing with the tide water, upon the reflux was carried out into the North Sea, while the flux of the tide westward came in pure water from the ocean. In this way the whole Carse deposit, which once extended from hill to hill, has been, in the space now occupied by the Firth, washed away into the ocean. Here, as the space of the Firth became wider, the waves had more room to rise higher, and the destruction of the Carse proceeded more rapidly, threatening at no distant period to wash out the whole. In order to stop this waste of the best land of the country, farm steadings having to be lifted back several times and the Castle of Errol swept away, Mr Crawford, proprietor of Errol, had engineers from England to prevent if possible the waste, but in vain. A near relation of the writer then proposed a means, a well-designed protection by stone walls, and he, employed by Mr Crawford, completely succeeded in preventing further destruction. This was effected more than a century ago. A deposit of mud along the north shore has now taken place, and reeds, salt grass, and other aquatics have formed lodgement, causing a farther deposition of mud, which is gradually contracting the scour basin of Tay Firth — a scour so necessary to prevent a further rise of the bar at the mouth of Tay, and the deposit of sand near Dundee harbour. At present the scour basin above Dundee extends to about 20 square miles, which was once all carse except a narrow strip of river. The amount of tide, flux and reflux, past Dundee twice a day is about 180 millions of cubic yards each, independent of the river flow. Now, seeing that there is gradual deposit and contraction of the scour basin above Dundee now in progress, any other barrier to the flow of scour upward and downward, such as a bridge, ought of all things to be avoided. A line of pier towers such as proposed, and especially those near the north shore, where the bend and longitudinal form of the pier tower directing the current outward from the front of the shores, is certain to cause sand deposit where it is most injurious to the harbour. The current passing between the piers will deepen the water in the line of the bridge, and especially towards the middle, where the spans are widest. This will render the bridge still less stable, while, especially at the north end and bend, a sandbank will form, shutting up the harbour. Altogether, the bridge piers must act to form sandbanks at a little distance from the bridge, upward and downward, and at the same time promote sediment deposit in the Firth above the bridge, diminish the amount of scour, raise the bar at the mouth of Tay, and render Dundee harbour less accessible.
Gourdiehill, Errol, December 4, 1869.