MR. T. M. EEADE AN ESTIMATE OF POST-GLACIAL TIME. 299 



Boulder-clay in the valleys of the Mersey, Dee, and E-ibble. This 

 post-glacial erosion preceded the deposition of the estuarine and 

 Peat- and Forest-beds, which lie on the denuded surfaces of the 

 remnants of Boulder-clay now occupying the valleys. His estimate 

 of 1 foot in 400 years for the valley-erosion was not excessive, 

 being ten times more than the present general rate of denudation. 

 He referred to the proofs of the surface of the Boulder-clay being 

 much eroded. He only pretended to give an approximate estimate, 

 which was really below the mark. He thought it possible to apply 

 a time-scale to certain beds. 



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