CHANGE OP LEVEL IN LANCASHIRE. 



439 



gaining on the land ; therefore what is deposited in front of the sand- 

 dunes is again swept away, and all that goes to the accumulation is 

 that which is blown over the tops of the hills or sand-cliffs. 



This will also be the case where the coast-line is stationary. 

 Again, the high sand-dunes form a barrier that the sand cannot so 

 readily surmount, the practical effect being that, the bases being 

 swept by the tide, and the angle of repose remaining constant, less 

 sand travels inland the higher they grow. At the mouth of the 

 Alt there is a very extensive bank at low water swept by the north- 

 west wind ; but the sand does not accumulate, as it is blown into the 

 river Alt and washed out seawards again. The land on which the 

 Altcar rifle-range is situated has, in fact, as a protection to the river, 

 been gained from the sea by the erection of artificial obstructions, 

 against which the sand accumulates. This accumulation has now 

 practically ceased ; and the river and the sea combined are eating 

 into the land by the Crosby lighthouse, and making sad havoc with 

 the submarine peat- and forest-bed. 



On referring to the map it will be seen that the blown sand is 

 narrowest at this point, though the conditions are very favourable 

 for its development, had the river Alt not intervened. 



If, then, it be conceded that the last change of level in South- 

 west Lancashire was a downward one, I think the facts and cal- 

 culations I have had the honour to lay before you pretty clearly 

 prove that it did not take place within the last 2500 years. 



Discussion. 



The Chairman (Mr. Hulke) remarked upon the economic as well 

 as scientific interest of the communication from the proved increase 

 of land in the area. 



Mr. De Rance, who had surveyed the district described by Mr. 

 Reade in his paper, could corroborate many of the author's conclu- 

 sions, especially by the finding of Roman coins on the surface of 

 the marsh land and by a Roman bath only 5 feet above high-water 

 mark. 



Prof. Jtjdd stated that Mr. Reade's conclusions were entirely in 

 accord with the most recent researches concerning the supposed 

 changes in the level of the shores of the Firth of Forth since Roman 

 times. 



The Author stated that at Hoylake, in Cheshire, numerous 

 Roman remains belonging to a Roman encampment a few feet 

 above high-water mark prove that no appreciable downward move- 

 ment has taken place since Roman times. He thought the actual 

 period required for the formation of the blown sand was probably 

 nearer 5000 than 2500 years. 



2g2 



