the Estuary of the Mersey. 115- 



phosphate of iron, of a brilliant blue colour. This mineral I hav& 

 found occasionally on the surface of bones taken out of peaty soil- 

 beds ; and at Birkdale, at one point immediately under the peat, 

 small concretionary lumps of clay contained it. It appears to be due 

 to the partial deoxidation of peroxide of iren,^ caused by decompos- 

 ing vegetable matter, and the union of the iron with phosphorus 

 left in the clay in the form of phosphates by decomposing animal 

 matter. Near the peat the phosphate of iron is more largely de- 

 veloped. Under the microscope this clay showed Triceraiium faviis — 

 a marine or brackish water diatom. For reasons which I have not 

 space to detail here, I am inclined to correlate this peat with the 

 Inferior Peat Bed} Doubtless much move of this ancient land-surface 

 would be brought to light were excavations made in creeks now 

 filled up, which from their position were formerly protected from the 

 full forces of the tides. 



Formby and Leasoive Marine Beds. — Lying upon> the denuded 

 surface of the inferior peat-bed, or where its destruction has been 

 complete, upon either the washed-drift sand or thin beds of re- 

 assorted gravel, resting on the Boulder-clay, or in some cases upon 

 the bare Triassic rocks, are a most important group of Post-Glacial 

 deposits. 



That the whole group is of marine origin I have fully satisfied 

 myself,- having found marine shells in these beds under the superior 

 peat and forest bed, exposed by tidal action at the mouth of the Alt^ 

 in the equivalent laminated grey clay at Birkdale, and in the clay 

 and silts between the inferior and superior peat-beds all along the 

 Cheshire coast. Marine shells were also found in cutting the sluices 

 between Formby and Ainsdale, and 20 feet deep in a well at High- 

 town. Among the shells which I have found in Lancashire are 

 Scrohicularia piperata, Tellina solidula, Turritella communis, Nafica 

 monilifera and Cardium edule. In Cheshire there is a greater variety. 

 No extinct species of shells or Arctic forms have been found in these 

 deposits. A diligent microscopical investigation of a great many 

 specimens from different localities has also disclosed, in nearly all 

 cases where the marine shells are absent, either Foraminifera, among 

 which Eotalias are the most frequent, or marine or estuarine forms of 

 Diatomacege. Six feet below the superior peat-bed and 3 miles in- 

 land, at Formby, I found Foraminifera in the laminated blue clay, as 

 also in a specimen taken from two feet below the sub-marine forest of the 

 Alt. Mr. F. Kitten, of Norwich, who has kindly examined my 

 specimens, detected in them the following Diatomaceee, all forms 

 which live only in salt or brackish water : Triceraiium favus, T. 

 striolatum, Coscinodiscus radiatus, Melosira Borreii, Fodosira maculata, 

 Tryhlionella gracilis, Nitzchia Brebissonii, Navicula Jennerii, N. minu- 



^ Mr. Vawser, Borough Engineer of "Warrington, tells me the surface of the 

 ground is between 19 and 20 feet above Ordnance datum. 



^ Mr. Chas. De Kance considers it to be a fresh-water deposit, and has termed it 

 Cyclas clay, and it is so called on the Map 90 S.E. ; but he must have been misled by 

 finding dead shells of Cyclas cornea thrown out in cleaning the drains or sluices exca- 

 vated through the peat into the blue clay. 



