60 The Ottawa Naturalist. [Aug.-Sept. 



of unconformity as that represented by a basal conglomerate. 

 Deposition was continuous throughout Levis time, as shown 

 by the fossils, but the conditions governing the character of the 

 sediments deposited were varied. 



Cliff Breccias. 



It is possible that certain intraformational glomerates whose 

 phenoclasts are angular and not rounded are largely made up 

 of cliff breccias. Certain of the unevenly graded glomerates as 

 mentioned above may have had their larger and angular material 

 derived from ridges or domes raised above sea level, as pos- 

 tulated by Walcott. 



Tectibreccias. 



For a full discussion of intraformational folds and breccias 

 of tectonic origin the reader is referred to W. J. Miller's paper: 

 "Notes on the Intraformational Contorted Strata at Trenton 

 Falls." The writer's visit to this interesting locality convinced 

 him of two important facts. Firstly, that the "contortions" and 

 breccias had taken place most characteristically in zones where 

 deposition of sediments had been varied and alternating. Second- 

 ly, breaking down of the folds was, locally, very pronounced; 

 extreme overthrusts of the hardened or purer limestone layers 

 resulting in the formation of edgewise breccias contained in a 

 greatly crushed and squeezed but structureless mass of shale. 

 It seemed obvious from a personal examination of this pheno- 

 menon, that the thin limestone bands must have been well 

 indurated before they were brecciated, and that the interbedded, 

 shaly limestones, because of their composition, took up the 

 thrust in such a way as to show little or no contortions or folds, 

 such as is shown in the stringers of brittle limestone contained 

 within them. The general overthrust phenomena exhibited in 

 the more massive beds of the Trenton formation and their asso- 

 ciation with the nearby Prospect fault, seem to point conclu- 

 sively to the tectonic origin of the contortions and breccias. 

 Intraformational breccias of this type are not to be confounded 

 with Fault breccias or Crush conglomerates. They are to be 

 expected in those portions of a formation which have under- 

 gone varied conditions of deposition and subsequent exogenic 

 deformation. As intraformations they are interstratified with 

 the formation in which they occur, and are never found in cross- 

 cutting position. It is also interesting to note that the pheno- 

 clasts of such glomerates should be of a different composition 

 and texture from the matrix. 



Ice-Formed Glomerates. 

 It is possible that icebergs and glaciers may have featured 

 in the formation of intraformational glomerates. The shoving 



