STRATIFIED DEPOSITS 



going into detail we may accept as a fact 

 that this formation of layers by stuff 

 brought down from the land by rivers and 

 washed from the coast-line by the sea waves 

 gives rise to what are called " stratified de- 

 posits." I will now show you some pictures of 

 this stratification. Here (Fig, 28) are shells 







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VvJt- 





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Fig. 28. — Photograph of a slab of Bognor rock (Lower 

 Eocene) showing embedded marine shells. 



embedded in the Bognor rocks deposited some 

 thousand million years ago ; there are many 

 sorts of shells, whelk-like shells and volute 

 shells embedded here. 



Whole skeletons of animals are sometimes 



45 



