REPORT OF THE STATE PALEONTOLOGIST 1901 551 



Tiz, the lowest, which then would appear to rest directly on 

 'Cambric beds; or that they may, as suggested by the reported 

 identification of Dictyonema flabelliforme, belong 

 to an upper Cambric or transitional zone, and that the Cam- 

 bric may, therefore, be also represented in this slate belt by 

 :graptolite shales. The fact that the middle and upper zones 

 found at the I>eep kill seem to be absent in the outcrops re- 

 ferred to by Dale, may also account for the small thickness of 

 the terrane reported by that investigator, as compared with 

 that found at the Deep kill. 



A striking feature of the Deep kill section, and one w^orthy of 

 special notice, on account of the still contested nature of the 

 habitat of the graptolites, is the regular periodic succession of 

 the rocks associated with the black graptolite shales within 

 the two lower zones. To demonstrate these cycles of depo- 

 jsition, the list of the beds is given in a more comprehensive 

 form. 



h limestones with shaly intercalations 



c sandy shales and grits 



d greenish silicious shale and black graptoUte shale 



€ thin bedded shales, grits and limestone 



f greenish silicious shale and black graptolite shale 



g greenish silicious shale 



7^ limestone 



i greenish silicious beds and black graptolite shale 



j greenish silicious beds and sandy shales 



A* limestone 



I greenish silicious beds and black graptolite shale 



m limestone 



n covered 



greenish silicious beds and black graptolite shale 



It w^ill be noticed that the deep black, soft graptolitiferous 

 mud shales are alw^ays inclosed in greenish gray, very hard, 

 thin bedded, more quartzose layers, and that between two 

 periods of deposition of these there is always intercalated one 

 of thin bedded, barren limestone. This alternation is pre- 

 «ented five times in the section. 



