Sir W. Dawson — The Animal Nature of Eo%obn. 449 



by plication alternating with strongly folded beds having the hai'der 

 ones dislocated ; others are merely bent or folded (Figs. 4 and 5). 

 It presents subordinate beds of different qualities, dolomitic, serpen- 

 tinous, or graphitic, and is imraediatelj^ associated with thin-bedded, 

 fine-grained gneisses, qiiartzite, and biotitic and hornblendic schists. 

 In some beds it has disseminated crystals of minerals usually found 

 in metamorphic limestones, while in others there are concretionary 

 masses, nodules, and grains of serpentine and pyroxene. Eozoon 

 in masses occurs only in certain layers, most frequently in those 

 which are serpentinous, but a careful examination detects in manj?- 

 layers, not showing perfect examples of Eozoon, small fragments or 

 patches having its characteristic structures, or detached chamberlets 

 or groups of these. The occurrence of these fragments I regard as 

 an important fact, and as showing that what may be termed "Eozoon 

 sand " enters largely into the composition of the limestone. 



In illustration of this part of my subject, I present a rough map 

 of the district near the Petite Nation Eiver, in rear of Papineauville, 

 referred to by Dr. Bonney in his valuable paper in the July Number 

 of this Magazine, and in addition to the section given in his paper, 

 one showing the order of succession in the valley of the Calumet, 

 a little stream some distance to the eastward. I also give examples 

 of the manner in which the associated gneiss, though often very 

 regular, is along certain lines contorted, and the manner in which, 

 in these contorted spots, the quartzite bands are cracked and broken, 

 exactly as may be observed in the shales and sandstones of the 

 Quebec group on the Lower St. Lawrence. 



I may add here that Dr. Adams has found that in certain localities 

 the rocks of the Grenville Series become almost horizontal, though 

 even in this case they show evidence of having been subjected to 

 much alteration and to lateral pressure. 



The summary of facts above given should, I think, be sufficient to 

 show that in the case of the Grenville limestone we have phenomena 

 which cannot be explained by mere pressure acting on massive' 

 rocks, or by segregation of calcite from igneous rocks, or by vein 

 structures, or by any contact structures arising at the junction of 

 igneous and aqueous deposits. We have, on the contrary, to deal 

 with a formation which indicates that in the early period to which 

 it belongs regular sedimentation was already in full operation. The 

 more precise vital and chemical agencies which prevailed in the 

 ocean of the Laurentian period we must notice later. 



I have merely to add here that the characters assigned above to 

 the Grenville Series have not only been fully corroborated by the 

 recent work of Adams and Ells in Canada,^ but also by the surveys 

 of Kemp and Smyth in the more disturbed and elevated district of 

 the Adirondack Mountains in New York.^ 



We have thus paved the way for the consideration of evidence 

 of a structural and chemical character. 



{To be continued.) 



1 American Journal of Geology, 1893, No. 4. Also Eeports Gaol. Surv. of Canada. 

 '^ Bulletin Geol. Soc. of America, March 1895. 



DECADE IV. — VOL. II. NO. X. 29 



