INCLUSIONS; ORGANIC REMAINS 717 



tions were uncovered, the first or highest of which supplying mate- 

 rial for the oldest beds was non-granitic. 



From the nature of the inclusions Berkey has been enabled 

 to determine that the quartz grains of the St. Peter sandstone were 

 derived from the gneisses and granites of the Canadian Old Land, 

 and that the Sylvania sands were most probably derived from the 

 older St. Peter sands, with which they agree in all respects. 



15. Organic Remains. Abundant remains of marine organ- 

 isms are generally a good criterion for the marine origin of the 

 strata containing them. There are, however, important exceptions 

 to this. Thus the foraminiferal limestones of India and South 

 Africa are formed as eolian deposits upon dry land, and often at a 

 distance from the shore, though the remains themselves are all 

 of marine types. Marine types may also be included in a terrestrial 

 deposit as a result of derivation from older marine strata by 

 weathering or erosion. Again shells of marine organisms may be 

 carried inland by birds and other animals (including man) and 

 become embedded in later deposits. Man-made shell heaps are 

 generally recognizable by the presence in them of human imple- 

 ments as well as evidence of fire, but shells carried inland by birds 

 are not readily recognizable as such. The occurrence of organisms 

 of marine types in relict seas distant from the coast must be con- 

 sidered. This subject will be more fully discussed in a subsequent 

 chapter. 



Occasional intercalation of marine layers in delta formations 

 otherwise of non-marine origin must also be noted here. Such 

 intercalations have been used to prove the marine origin of an en- 

 tire formation, the bulk of which is most probably of terrestrial 

 origin. 



Fresh water and terrestrial organisms when exclusively found 

 in a formation indicate a continental origin. But such remains 

 may be as characteristic of fluviatile as of lacustrine deposits and 

 often more so. Thus the remains of land vertebrates and of plants 

 in a formation indicate more commonly river, flood-plain, swamp, 

 or, in the case of the vertebrates, steppe deposits, the remains being 

 embedded in the river muds or covered by blown sands. Abundant 

 remains of fresh water molluscs, Crustacea, etc., of Chara and other 

 fresh water plants, indicate a lacustrine or paludal origin of the 

 formation containing them. 



Terrestrial organisms, especially plants, may also be carried out 

 to sea and so become embedded in marine formations. The same 

 thing is true of river-inhabiting fish, Crustacea, and Mollusca. The 

 extent of such transportation is generally determinable, as shown 



