Vol. 52.J REV. E. HILL ON TRANSPORTED BOULDER CLAY. 



305 



buoyancy of the ice would make the 

 masses at first practically weightless 

 in the water, so there would be 

 nothing to press down the floor on 

 which they sank. As the ice melted 

 away they would acquire weight, 

 but meanwhile deposition would be 

 going on all round. As the encom- 

 passing ice melted still further, por- 

 tions of the outside would break 

 away : hence the patches. Mud also 

 from the wet outside would ooze off 

 and spread on the sand floor, forming 

 the tongues and strings. In all 

 these the chalk would have dis- 

 appeared, as it has disappeared from 

 recomposed Boulder Clay, and gene- 

 rally from parts where water can 

 percolate. Meanwhile the progress 

 of deposition would have intermixed 

 sand with the patches, tongues, and 

 strings in undisturbed stratification. 



The other group of transported 

 masses is different in character, 

 date, and locality. The group came 

 under my notice in my own parish 

 (Cockfield, Suffolk). Here is a series 

 of pits, containing a peculiar gravel, 

 which I have traced along a line of 

 about 7 miles, through the parishes 

 of Bradfield, Stanningfield, Cock- 

 field, and Lavenham. Their contents 

 resemble descriptions of ' Cannon- 

 shot Gravel ' : they lie at correspond- 

 ing levels along the slope of an 

 existing valley, which is hollowed 

 out of Chalky Boulder Clay ; and 

 they probably mark an earlier water- 

 course. They clearly indicate exten- 

 sive denudation of the Boulder Clay, 

 for the slopes of that formation rise 

 from 40 to 60 feet above them ; also 

 the flints which it contains are clean 

 of chalk, and have undergone con- 

 siderable wear. In two of these pits, 

 one near Cockfield ' Abbey ' and one 

 near Willow Bridge (the latter lately 

 filled in), masses of Boulder Clay are 

 found lying on the top of the gravel. 



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