8 Jackson, Facetted Pebbles with Glacial Deposits. 



Apart from the association of the Wirral facetted pebbles with 

 Glacial deposits (in these cases the beds are said to be Upper Boulder- 

 clay) is the further interesting fact that, as at Pendleton and Kersal 

 Moor, the pebbles are mainly split or fractured stones, which have 

 been modified by wind action. 



2. The Geological Horizon and Significance of the 

 Facetted Pebbles 



As already pointed out, in the Pendleton and Kersal Moor 

 localities the facetted and wind-worn pebbles occur in a well-defined 

 zone overlying the Glacial deposits and immediately below a Neo- 

 lithic floor. At Hilbre Point, in the Wirral, they are similarly situ- 

 ated as regards the Drift and Neolithic deposits, while at Dove Point, 

 in the same neighbourhood, they overlie what is regarded as Upper 

 Boulder-clay. Here, however, a whole series of beds occur super- 

 imposed above the facetted pebble zone, indicating important changes 

 in the relation of land and sea in post-Glacial times. Some of these 

 changes have undoubtedly taken place during Neolithic times. The 

 general succession of these beds has been studied by C. E. de Ranee, x 

 T. Mellard Reade, 2 G. H. Morton, 3 and others. From these observers 

 we learn that the area occupied by these interesting deposits extends 

 over the coastal portions of Lancashire and Cheshire, forming a low- 

 lying plain stretching inland for several miles. Its inner margin is 

 fairly well defined by the 25-foot contour-line, but a large part of its 

 surface is low ground below sea-level, the sea being kept out in some 

 places by a long range of sand-dunes that fringe the coast-line, in 

 others by artificial embankments. 



The succession of the beds at Dove Point is given by Morton 4 

 as follows : — 



(1) Blown Sand, 15 feet. 



(2) Soil-bed, 2 feet. 



(3) Peat -bed, 1 foot. 



(4) Blue Clay, 1 foot. 



(5) Upper Forest-bed, 3 feet. 



(6) Blue Clay, 2 feet .6 inches. 



(7) Lower Forest-bed, 1 foot. 



(8) Boulder-clay. 



The Leasowe Embankment has since been extended towards 

 Hoy lake and some of the upper beds have been covered up by it. 

 The lower beds of the section have also suffered denudation by the 



1 De Ranee, "On the Post-Glacial Deposits of Western Lancashire and 

 Cheshire, "Quart. Journ. Geol. Soc, XXVI., 1870, pp. 655-668. 



2 T. M. Reade, " The Geology and Physics of the Post-Glacial Period, as 

 shown in the Deposits and Organic Remains in Lancashire and Cheshire," Proc. 

 Vpool. Geol. Soc, 1871-1872, pp. 36-88. (Reprint, pp. 1-53.) 



3 G. H. Morton, Geology of the Country around Liverpool, second edition, 

 London, 1897, pp. 228-272. 



4 Morton, op. cit., p. 235, and Plate XVI., Fig. C. 



