Submergence. 417 



detritus which covers much of the lower parts of Scotland 

 and of England, composed of clay, mixed with stones and 

 great boulders, many of which are scratched, grooved, 

 and striated, in the manner of which we have experience 

 in the glaciers of Switzerland and Norway. Sands and 



FIG. 85. 



Natica clausa. Turritella communis. Aporrhais pes-Pelicani. Scalaria Grcenlandica. 

 Group of Post-Pliocene Fossils, Clyde beds. 



gravels, with perfect sea-shells, are interstratified with 

 these boulder-beds, and sometimes the clays themselves 

 contain unbroken shells, as, for example, in the low 

 ground of Shropshire between Coalbrook Dale and 

 Wellington. Here and there, even in the heart of the 



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