238 Correspondence — Mr. Mellard Reade. 



coI^I^Es:F'OI^^x)EI^^c:E. 



FORMBT AND LEASOWE MARINE BEDS, OR THE SO-CALLED 

 " CTCLAS CLAY." i 



Sir, — On referring to the Explanation of Geological Map 90 S.E., 

 I can find no reference to a Loioer Scrobicularia Clay ; on the con- 

 trary, the so-called Lower Cyclas Clay is stated to underlie the main 

 peat from Eimrose Brook to Birkdale. Nor does Mr. De Eance's 

 paper on the Post-glacial Deposits of Western Lancashire and 

 Cheshire help the matter at all, for the only reference I can find is 

 to a Lower Scrobicularia Clay occurring in Cheshire — a clay well 

 known before either of us devoted any attention to the subject. 

 These papers, adduced along with others I have not seen, as evidences 

 to the contrary, ignore the existence of any Lower Scrobicularia 

 Clay in Lancashire, as much as does Geological Sheet 90 S.E. 



This being the case, I submit that it is legitimate to conclude that 

 Mr. De Eance knew nothing of any Lower Scrobicularia Clay in 

 West Lancashire at the time he penned the papers quoted above. 



But whether Mr. De Kance did or did not at that time recognize 

 the existence of a marine lower clay is a matter of very little im- 

 portance in comparison with the necessity for accuracy of description 

 on the Geological Survey Sheets. As he still clings to the Cyclas 

 Clay, but now adopts the qualification that the larger portion of 

 these clays in Lancashire are of freshwater origin, it will be neces- 

 sary for me to re-state my reasons for considering the deposits in 

 question to be marine. 



Before seeing the description of Sheet 90 S.E., I had devoted some 

 time to the Post-glacial geology of the district ; and though I had 

 hitherto seen nothing but marine or estuarine clays, I never thought, 

 with such authoritative statements before me as the Map and its 

 description contained, of questioning the existence of large fresh- 

 water deposits in the neighbourhood. One of the first steps I took 

 to test the character of the clay was to have a hole about 6 ft. by 3 ft. 

 sunk through the main or superior peat and forest-bed at the Alt 

 mouth, where it is described by Mr. De Eance ^ to rest upon Lower 

 Cyclas Clay, and at a depth of 5ft. Gin. from the surface came upon 

 a thick bed of Tellina solidula and Cardium edide. 



Again, at Birkdale, when carrying out the main outfall sewer, 

 upwards of a mile long, and penetrating the superior peat through- 

 out its length to the grey clay below, numerous marine shells were 

 found, hut not one freshwater shell, though strict injunctions were 

 given to the Clerk of the works that all shells found should be pre- 

 served. The shells found were Scrobicularia piperata, Turritella 

 communis, Cardium edule, Tellina solidula, Buccinum undatum, and 

 Natica monilifera. 



Also at the Brickcroft, near the "Ash Tree Inn," Birkdale, 

 which I frequently examined while the clay was being cast, I found 



* Explanation of Geological Sheet 90 S.E. 



