COMPARISON OF DATA CONCERNING INCLOSING SEDIMENT 



429 



Data as to inclosing Sediment classified and compared 



a. for species occurring more than. once in the same section 



Table III, — TaMc classifying the sediment data for species occurring more 

 than once in the same section 



Type of gradation in passing from 

 older to younger strata. 



Number ot 



species showing 



gradation. 



Number of 

 species occur- 

 ring in both 

 facies of inter- 

 bedded series. ; 



Number of 

 species occur- 

 ring at ap- 

 proximately 

 same horizon, 

 records in- 

 definite. 



Shale to liniestone .... 



1 ! 



7 

 



10 

 2 

 2 

 





Limestone to shale 



Limestone to shale to limestone 



Sandstone to limestone , 



7 

 4 



Sandstone to shale 





Shale to sandstone ; . 







Sandstone to shale to sandstone. . . 

 Limestone, shale, and sandstone . . . 







Perhaps the most interesting features of the preceding table are (a) 

 the fact that no discovered species of Cambrian Brachiopoda is in any one 

 section common to limestone, shale, and sandstone ; (h) the pronounced 

 affinity of single species for both facies of an interbedded series com- 

 posed of shale and limestone; and (c) the relatively high percentage of 

 species able to accommodate themselves to a vertical change from sand- 

 stone to limestone and the absence of any species exhibiting the reverse 

 progression. 



B. FOR ALL SPECIES OCCURRINC MORE THAN ONCE 



Table IV. 



-TaWe classifying the sediment data for all species occurring more 

 than once 



Type of gradation in passing from 

 older to younger strata. 



Number of 



species 



occurring 



in the same 



section. 



Number of 



species 

 occurring 

 in adja- 

 cent 

 sections. 



Number of 



species 



occurring 



in the same 



province. 



Number of 



species 

 occurring 

 in different 

 provinces. 



Coarse to fine 



31 « 

 14 8 



15 

 4 



10 



2 



5 



Fine to coarse 



1 







Total showing gradation. 

 Total actually or apparently 

 occurring in different sedi- 

 ments of the same age 



45 



25 



19 

 6 



12 

 32 



6 

 20 



^ The four limestone-shale-limestone and the two sandstoue-shale-sandstone gradations 

 of Table III are credited to each of these figures ; their elimination leaves the ratio of 

 coarse-fine to fine-coarse, as 25 to 8. 



XXX — Bull. Geol. Soc. Am., Vol. 25, 1913 



