424 PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 10, 



To what portion of the Azoic ages this series is to be referred we 

 cannot yet say. Palaeontology gives little aid in solving the ques- 

 tion, and the composition of the felspars, <fec., is not known. But 

 that it is older than the Huronian series seems, to say the least, 

 highly probable ; for, 



1. In the varied character of its deposits and the abundance of 

 limestones, together with the extreme alteration of many of the 

 beds, it resembles the " Laurentian " of Canada, and the Azoic region 

 lately separated from the Silurian system in Southern New York 

 and New Jersey * 



2. It is unconformably overlain by a great thickness of deposits 

 similar to the " Huronian" series, and subordinate to those which 

 in this quarter represent the Potsdam period f. 



III. HUKONIAN POEMATION (COLDBROOK GkOTJP J). 



Between the Azoic or Laurentian and the Lower Silurian sedi- 

 ments a thick series of beds intervenes, differing in character from 

 both. These rocks extend in two bands, one north-east from the 

 City of St. John, the other parallel to it, but further south, each 

 about thirty miles long and three or four wide. They consist of — 



Lower Division. 



1. Coarse red conglomerate (with an abundance of quartz peb- 

 bles) and red sandy shale. 



2. Dark porphyritic slates and trap, with slate, conglomerate, 

 trap-ash, and tufa. 



3. Grey and ferruginous arenaceous shale and sandstone, becom- 

 ing, when altered, a laminated compact felspar or felspathic quartzite. 



4§, Pale-green (weathering grey) slate, stratification very obscure 

 [apparently an indurated volcanic ash, Dawson'], with slate-conglo- 

 merate, ash-beds, and tufa. 



Upper Division. 



5§. Eed and grey conglomerate and red shale. Eed and purple 

 grit and sandstone. 



Of these beds, nos, 1, 2, and 3 do not extend so far west as St. 

 John, and no. 4 diminishes very much in bulli in the rear of the 

 city, where it fills inequalities in the uppermost beds of the Port- 

 land series. While further west, at the head of the harbour, the 

 remnants of this Huronian series (nos. 4, 5) are only 150 feet 

 thick, yet at Loch Lomond, ten miles eastward, the whole forma- 

 tion measures vertically not less than 7000 feet ! 



These figures indicate that the ancient continent, previously ele- 



* See ' Silliman's Journal,' 1865, p. 96. 



f Further details respecting this series, and all the overlying formations 

 found in the counties of St. John, King's, and Albert, will be given in the Re- 

 port on the Geology of Southern New Brunswick, already alluded to, written 

 and arranged by Prof. Bailey, and published by the Provincial Legislature. 



J This and the succeeding division (St. Johii group) have such a variety of 

 members, and represent so great a lapse of time, that they deserve to be called 

 formations rather than groups. 



§ These are equivalent to nos. 1, 2, 3, and 4 of the section given in ' Geology 

 of St. John county.' 



