A HISTORY OF LANCASHIRE
inasmuch as it brings us nearer to the historic period. It consists of a second plain formed entirely by the deposition of marine or estuarine sands, muds, and clays. These beds nearly all lie below the 25-feet contour and are the mixed detritus and sediments brought down by the Mersey, Ribble, and Lune, which have been sorted and deposited on the coast between the mouths of these rivers. The lands over which the Liverpool and Southport Railway runs are part of this plain of deposition, which has added many square miles to what is now the county of Lancaster.
The muddy sediment, of which these 'Formby and Leasowe Marine or Estuarine Beds' are composed, is crowded with Foraminifera, as was proved by borings at Altcar, recently made by the Lancashire and Yorkshire Railway.[1] The mollusc Scrobicularia piperata, in a vertical position as it lived, also occurs, showing that some of the beds were laid down between tide marks.
Perhaps the most interesting deposit of all is the peat and forest bed, which was known over a century ago. A description and plate of it appeared in the Gentleman's Magazine in 1796, p. 549. This bed underlies the moss lands, and upon it the sand-dunes previously described in the chapter on Geology have been built up by the wind. They occupy an area between Liverpool and Southport of 22 square miles.
The outcrop of the peat and forest bed at and south of the Alt mouth is still to be seen, but it has of late been much destroyed by the inroads of the sea.[2]
Geologically the most interesting fact in connection with the extensive post-glacial deposits is the proof they afford that oscillations of the land with respect to the sea level have taken place in very late—probably miocene time (see Dawkins' Prehistoric Man)—geological times. The peat and forest bed with stools of oak, birch, and pine are washed by the tide now at the Alt mouth, and elsewhere they have been proved by dock and other excavations to occur below low-water mark—situations where it would be impossible for trees to grow now.
This belt of alluvial deposits extends northwards with little interruption past the Fylde country to the mouth of the river Lune, and with some intervals extends to the river Duddon. Here knolls of boulder clay rise through the moss lands and are distinguished by their greenness. Excellent sections of the deposits and underlying boulder clay and rocks were disclosed in the excavations of the Midland Railway dock at Heysham, and are described in the Proceedings of the Liverpool Geological Society, session 1901-2 (Reade).
All the fringes to the solid land of south-west Lancashire are but parts of an extensive belt of deposition, remains of which occur all round the British Islands. Still more extensive plains form a large part of Belgium, and the excavations for the Bruges Ship Canal presented excellent sections showing a similar series of estuarine and peat beds with the remains of trees.[3]
Before artificial drainage and pumping was resorted to, much of the land was little better than a series of marshes, and many meres, such as Martin Mere, near Southport, existed, but on a smaller scale. The land is now under cultivation, excepting where built upon, as at Southport and Birkdale, and is peculiarly favourable to the growth of potatoes, which are produced in great quantities. The more sandy portions are in some cases used for growing asparagus, which seems to like the soil and saline surroundings.
The mean rainfall at Park Corner, Blundellsands, for twenty-nine years, 1876-1904, is 29.95 inches.
Enough has been said to show that this desolate-looking coastal plain abounds in lessons of the greatest interest from a geological, historical, and a human aspect, lessons of a kind that are absent in more beautiful landscapes.
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