9()4 GKABAIJ AND O'CONNELL THE GRAPTOLITE HHALES 



else they would show a good representation of marine organisms, whereas 

 they contain only graptolites. The grits into which the shales pass later- 

 ally must have been deposited wholly above sealevel, since they are devoid 

 of all organic remains except worm tracks and the traces of fluviatile 

 organisms. 



Conclusions 



From tlic two illustrations which we have cited we may draw the fol- 

 lowing conclusions: In the Swedish region, since the graptolite shale 

 facies follows immediately, without even a sandstone facies, on an eroded 

 land surface, the muds must have been deposited along shore and not 

 even a few miles out to sea, since in every case there fails to appear any 

 nearer shore facies than the black shales themselves. Moreover, the ab- 

 sence of a normal marine fauna, made up of members from several phyla 

 at least, shows that the muds could not have been deposited in the deeper 

 littoral portions of the sea, as claimed by many writers, because, so far as 

 our knowledge allows us to judge, there is no portion of the littoral .zone 

 of the sea, be it near to or far from shore, that is devoid of an abundant 

 and varied fauna consisting of many genera, species, and individuals from 

 many classes of organisms. In southern Scotland we have a great tor- 

 rential deposit, with a maximum thickness of 4,000 feet of conglomerates, 

 grits, sandstones, and flags, passing into a black shale series which con- 

 tains only one class of organic remains — the graptolites. We interpret 

 these shales as mud deposits on the floodplain and in the lagoons of a 

 large delta or series of deltas, where periodic high tides washed in the 

 planktonic graptolites and stranded them on the flats, where they were 

 quickly buried in the shifting muds. Occasionally the graptolites were 

 swept far inland to regions where the distributaries of the delta were 

 spreading out even coarser sediments, for at times the graptolites, much 

 worn and broken, are found in the conglomerates, associated with worm 

 tracks and eurypterid fragments. So far, then, as we may draw conclu- 

 sions from a consideration of the two localities cited, it would seem that 

 the graptolites which were holo- or epiplanktonic were buried in deposits 

 more nearly of terrestrial than of marine origin, 



