92 L. "W. BAILEY ON GEOLOGICAL CONTACTS AND ANCIENT 



strata of the most diverse character, and that, while at one point the Primordial rests npou 

 what appear to be the most recent of these strata, at another it reposes upon beds which 

 ■cannot be less than several thousands of feet lower in the series, while the conglomerates 

 which mark its base bear further testimony, both in their composition and their thick- 

 ness, to the erosive processes which preceded or accompanied the deposition of the Pri- 

 mordial sediments. Finally, while local unconformable contacts may be seen at many 

 points, an equally marked discordance is observable in the two groups as a whole, the 

 trends of the Primordial being transverse to those of the supposed Huronian, as the folds 

 and dislocations of the one are cjuite independent of those of the other. The Lower Silu- 

 rian, or Cambrian, formation is thus as clearly defined in its stratigraphical relations as it 

 is in its paleontological features, and forms a readily recognizable horizon, with reference 

 to which the position of both older and more recent groups may be directly compared. 



As regards the older systems to which reference has been made, New Brunswick has 

 been naturally looked to as likely to afford some information upon the questions which 

 have recently awakened so much attention, regarding the number and order of succession 

 of the pre-Cambriau rocks, and has, indeed, been frequently referred to in discussions of 

 this subject. It can, however, I think, hardly be said that these questions, as here applied, 

 have yet received a definite solution. That there are among the rocks referred to three, 

 if not four, distinct groups of strata, exhibiting strong lithological contrasts, and pro- 

 bably representing entirely distinct periods and conditions of deposition, was early recog- 

 nized and has been confirmed by all later study of the region, but the precise relations in 

 which these stand to each other and their correlations with proposed subdivisions of 

 Archean rocks elsewhere, are not so easily settled and have been variously regarded by 

 different observers. Thus, while the writer, in common with Mr. G. F. Matthew, by whom 

 the structure of the district was first studied, has described, in what he believes to be an 

 ascending succession, a gneissic, a calcareous, a felspathic, and a schistose grou.p, — the two 

 former being regarded as representing the Laurentian and one at least of the latter the 

 Huronian system, — Dr. Hunt has been disposed to c[uestion the existence of true Lauren- 

 tian in this district, and to modify the above arrangement by associating the calcareous 

 with the schistose group, regarding both as newer than Huronian and ec[uivalents of what 

 he has elsewhere termed Montalban. "Without attempting to deny that such an arrange- 

 ment is possible, and that, if sustained by further investigation, it would bring the succes- 

 sion in this region into remarkable parallelism with that observed elsewhere, the 

 writer, after long and repeated stiidy of the region, is still constrained to think that the 

 facts of the case are such as to favour the former rather than the latter view of the actual 

 structure. Thus, applying the test of contacts, which it is the purpose of the present paper 

 more particularly to consider, it is not a little remarkable that while the calcareo-silicious 

 group may be seen at many points resting upon, and in direct contact with, the coarser 

 gneisses, following these throughout their distribution, and apparently involved in the 

 movements by which they have been affected ; nothing at all resembling the strata first 

 named is to be found in connection with the schistose group, where the few limestones 

 which are met with are very impure, of insignificant thickness, of different character, and 

 of wholly unlike associations. Again, if the calcareous and associated strata are really 

 more recent than the felsite-petrosilex group, the entire absence of the latter between the 

 same calcareous beds and the underlying gneisses, when these are observed together, 



