tJie Estuary of the Mersey. 117 



clay, and I ascribe its formation to snb-aerial aqueous erosion 

 during this the last period of elevation. The superior peat and 

 forest bed lies upon the Formby. and Leasowe marine-beds, and 

 contains at its base the remains of an ancient forest or forests. The 

 oak, pine, hazel, alder, birch, etc., are among the ti'ees found in it, 

 and may be seen with stumps erect and roots striking deeply 

 down into the blue clay at the Alt mouth. In some places only the 

 roots are seen striking into the clay, the bole having rotted away 

 and the roots being only covered by a thin layer of peat. 



With this bed I correlate the peat-bed of old Wallasey Pool, now 

 occupied by the Birkenhead Docks, the 40 feet of peat filling up the 

 Eimrose gulley, the peat-beds under the blown sand at Waterloo, the 

 upper bed in the Custom House section, before referred to, the land- 

 surface of the little creek at Garston, and the beds covering nearly the 

 whole areas of the previously-mentioned deposits; the average depth of 

 which will probably be about 7 feet, though in some localities 12, and in 

 one North of Scarisbrick 20 feet thick. The inland margin rests gene- 

 rally upon the washed-drift sand, as also does part of the peat near 

 Martin Mere. 



Becent Deposits. — Since the last-mentioned forest grew, the land 

 has gradually subsided to its present level, and probably the resulting 

 obstruction to the drainage has been the cause to a large extent of the 

 peat-beds. That part of the peat is due to this cause is proved by the 

 occasional intercalated beds of silt, in one case at Birkdale containing 

 marine shells.^ A long pause (certainly in commencement Pre-Eoman) 

 ensued, as is shown by the levelling up of all the depressions of 

 the superior-peat bed with marine or tidal silts, assisted by alluvium 

 brought down by rivers during floods. This levelling is so com- 

 plete, and from the levels the later stages of it must have been so 

 slow, that it measures a very considerable lapse of time. Bones of 

 Cetaceans have been found in this silt in excavations for the 

 Liverpool and the Birkenhead Docks. 



Denudation and deposition invariably go together, and we find 

 that below tidal mark the superior peat and forest bed has itself been 

 subject to gi-eat denudation, being only preserved where occurring in 

 sheltered inlets or creeks. That the land on the Cheshire coast 

 extended considerably seawards I consider an incontestable fact. 

 Areas of deposition and denudation are also continually changing. 

 and consequently we find recent deposits in places where the former 

 land-surface had been denuded; and this change, it must be borne in 

 mind, takes place without any relative alteration of the levels of sea 

 and land. 



Blown Sand. — Among the most recent deposits is that of blown 

 sand covering the superior peat-bed to a considerable distance inland 

 all along the coasts of Lancashire and Cheshire, and rising into high 

 sand dunes as it fringes the sea-margin. The present shore being so 

 extremely flat is eminently favourable to the generation of blown 



1 Mr. Einney and Mr. Talbot also found an intercalated bed of blue silt by Down- 

 holland Brook. — See *' On the Petroleum found in DownboUand Moss," Mancbester 

 Geological Society's Proceedings, March, 1843. 



