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PRINCIPLES OF STRATIGRAPHY 



(a) Granular, the texttire of the fine organic oozes. 



(b) Oolitic, consisting of minute spherules or oolite grains. 



(c) Earthy texture. 



(d) Compact conchoidal, as in coal, etc. 



The following table gives some of the principal hydrogenic and 

 biogenic rocks (Grabau-9) : 



Table of the principal types of hydrogenic and biogenic rocks. 



