1865.] MATTHEW SOUTHERN- NEW BRUNSWICK. 425 



vated above the sea, sank under the accumulated weight of Huro- 

 nian sediment to the extent of one mile and a half or more in that 

 short distance, and that a coast-line near the position now occu- 

 pied by the city limited the Huronian sea to the eastward during 

 a great part of this period. 



Its opening, if we may judge by the lowest number known, was 

 marked by the accumulation of littoral sediment. To this suc- 

 ceeded an epoch when igneous eruptions commingled molten matter, 

 scoria, and fragments of rock with the fine mud resulting from the 

 wearing of the Azoic continent. After an interval of time, during 

 which the arenaceous shales of no. 3 were formed, these conditions 

 were again repeated in a still greater accumulation of volcanic 

 ashes, tufa, &c., which, as the preexisting land sank beneath the 

 waters, spread as a thin deposit further west. 



The whole was eventually covered by the red and purple sedi- 

 ments of the Upper Division, which are more uniformly distributed, 

 and are conformably surmounted by the lowermost strata of the 

 Lower Silurian formation, thus becoming, like the Cambrian of 

 Britain, the "basement segments of the Silurian System." And 

 although Prof. J. I>. Dana classes these fundamental rocks of the 

 Palaeozoic series as Azoic, he remarks, that " should the Huronian 

 rocks be hereafter found to contain any fossils, they will form the 

 first member of the Silurian." 



In general characters there is a remarkably close resemblance be- 

 tween this formation and the Huronian of Canada, notwithstanding 

 the wide extent of country which intervenes. Both are largely 

 composed of erupted materials, diorites, tufas, and volcanic mud: 

 hardness and obscurity in the lamination of the slates is a feature 

 in common ; and here, as in Canada, slate-conglomerates may be 

 seen of a texture so compact and imiform that the enclosed masses 

 are distinguishable only by a difference of colour. There is even a 

 parallelism in the different members between the Acadian series and 

 that at the Bay of Mamainse, on Lake Superior, and at Thessalon 

 Eiver, Lake Huron, at which latter place the whole Huronian 

 series is supposed to be present : — thus, nos. 3, 4, 5, and 6 of the 

 section given at pp. 55-57, ' Report Geological Survey, Canada,' 

 1863, indicate the prevalence at succeeding periods in the region of 

 the great lakes of conditions similar to those which obtained in 

 Southern New Brunswick during the formation of nos. 1,2,3, and 4, 

 or the lower division of the Coldbrook ; while the higher members at 

 Thessalon Biver are an accumulation of sediments on a larger scale, 

 but resembling those of the Upper Coldbrook, and the passage-beds 

 to the Lower Silurian formation. I may also add that the passage- 

 beds in their eastern extension are overlain by igneous rocks, which 

 intervene between them and the Primordial shales. 



Considering, therefore, the origin of these deposits as well as 

 their position relative to the more ancient series and the Lower Si- 

 lurian beds above, we have little hesitation, notwithstanding that 

 the latter are conformable to them, in assigning these semivolcanic 

 sediments to the " Huronian series " of Logan. 



