294 ME. T. M. EEABE A.'N ESTIMATE OE POST-GLACIAL TIME. 



the gravel may have been reworked up by the sea. Borings from 

 Weston Point to Hale Head showed the presence of gravel, peat, 

 and sand below the present bottom *. 



Length of Time represented by the foregoing Post-glacial 

 Geologic Changes. 



That these changes rei^resent a very considerable lapse of time, 

 seems to me almost self-evident ; but how can we obtain a true scale 

 with which to measure it? In making the attempt it will be better 

 to reverse the order in which we have described the events, and begin 

 with the latest deposits. 



In a paper on " The date of the last Change of Level in Lan- 

 cashire "t, I have attempted to show, from observatioDS made of 

 the rate of accumulation of blown sand at Blundellsands, that the 

 minimum time required for the accumulation of the 22 square 

 miles of blown sand between Liverpool and the Ribble must be put 

 down at 2500 years, and that no appreciable change of level has 

 taken place in the coast-line within that period. History does not 

 go quite that far back ; but so far as it does (that is to the time of 

 the Eoman occupation of Britain), there is no evidence of any value 

 pointing to any change of level having taken place ; nay, what 

 evidence there is is strongly the other way. The Eoman fords on 

 the river Dee show plainly that the state of things then was much 

 as it is now X' 



The Eoman remains found at Hoylake came from a stratum of 

 soil above the peat-and-forest bed. It is evident from this that the 

 peat-and- forest bed was in existence in Eoman times in much the 

 same condition in which it appears now. It is in consequence of 

 being buried by blown sand that such numerous evidences of Eoman 

 tenancy have been preserved at Hoylake. The Eoman station was 

 probably situated just inside of the sand-dunes, which have since 

 encroached upon it and entombed its remains. I know of no 

 implements or other evidences of human handiwork having been 

 found either imbedded in the superior peat or in the silts below, 

 but I have found them in the superficial layers lying on the peat. 

 I am satisfied that 2500 years is a reasonable minimum limit to the 

 beginning of the present condition of level of land and water ; but 

 it may be much older. The superior peat-and-forest bed represents, 

 as I have attempted to show §, a continental connexion with these 

 islands, and if so, the land must have subsided not less than 200 ft. 

 since the connexion existed. 



2^ow comes our difficulty : What rate must we allow for the sub- 



* "The Mersey Tunnel, its Geological Aspects and Results," Proc. of 

 Liverpool Geol. See. for 1884^5. 



t Quart. Journ. Geol. Sec. Aug. 1881, vol. xxxvii. pp. 436-9. 



J See paper by the late Mr. R. Bostock, Proc, of Liverpool Geol. Soc, March 

 8th, 1870. An examination of the Roman Wall lately disclosed by excavations 

 in the Roodeye has satisfied me that the level of Chester, in relation to the sea, 

 is practically notv what it was in Roman times. 



§ See " Post-glacial Geology of Lancashire and Cheshire," before referred to. 



