326 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



report of 1870-71, and are also briefly mentioned in the report of 1876-77. They comprise 

 the former so-called pale argUHte group. They are superimposed upon Cambro-SUurian rocks 

 and extend from the St. Croix River, near Spragues Falls, to the Charlotte County Hne and 

 thence into York. At the hne of contact the dips are nearly vertical, but there is in places an 

 apparent conformabUity between the dark ar^Uite portion of the Cambro-SUurian and the 

 series under discussion. It is probable, however, that 'faults occur at the line of contact, as the 

 beds of fossihferous Silurian so well developed about Oak Bay, on the south side of the Cambro- 

 Silurian belt, are entirely wanting along the northern margin. The Devonian age of these rocks 

 has been based by Mr. Matthew upon the occurrence of remains of Lepidodendron, * * * 

 as well as from certain graphitic films, supposed to be the impression of fern leaves, found in 

 the eastern extension of these beds into Queens County. They also possess many points of 

 resemblance, lithologicaUy, to the typical Devonian Mispec, and hence they have provisionally 

 been assigned to this horizon. 



Doubt is cast upon the Devonian age of these rocks, as the Mispec group is 

 now known to be meso-Carboniferous.^^* (See p. 331.) 



The Devonian rocks of the St. John-Lepreau-Perry area have been the subject 

 of much discussion as to their true age and have been considered Carboniferous on 

 account of hthologic resemblances. The latest contribution from the Canadian 

 Siu-vey is by EUs/^® as follows : 



One of the most interesting of the geological formations which occur in this portion of New 

 Brunswick is that known as the Perry sandstone group. * * * -pj^g xocks consist of con- 

 glomerates, sandstones, and shales, generaUy reddish in color, but occasionally, in the lower 

 portion, some of the heavier sandstones and conglomerates become grayish. Plant stems are 

 quite abundant in some of the shale beds, both ia the rocks of Perry and near St. Andrewis. 

 These were carefully studied many years ago by Sir WUham Dawson and several papers relating 

 to their character and age were published by him between 1861 and 1870, in which their horizon 

 was placed as the upper portion of the Devonian system. The same conclusion had been 

 reached at an earlier date by Dr. Jackson and adopted by Prof. Rogers, after an examination 

 of the material from the plant beds of Perry, Maine. 



In the report by Bailey and Matthew, 1870-71, the opinion is expressed that the rocks of this 

 group are referable to the base of the Lower Carboniferous, rather than to the Devonian, from a 

 supposed lithological resemblance to certain conglomerates which are found in Kennebeccasis 

 Bay, an arm of the St. John River, where these rocks are assigned to the Carboniferous horizon. 



In Charlotte County the Perry group can be well studied in the peninsula extending from 

 the base of the Chamcook Mountain to the point at St. Andrews where the exposures are prac- 

 tically continuous for a distance of about 5 miles. The beds are cut across by several dikes 

 of green diabase which have altered the sediments at their contact. Similar dikes are seen on 

 Minister's Island to the east. 



The lowest beds of the group at Chamcook Mountaia consist of a coarse, heavy conglomerate 

 with pebbles, often of large size, for the most part derived from the felsitic rock of which the 

 mountain is composed. These conglomerates are a conspicuous feature in many places at the 

 base of this series of rocks, and they also occur occasionally as intermediate beds higher up in 

 the series. They are well exposed in the bluff east of Chamcook Harbor, on the islands and on 

 the shore at the entrance to Digdeguash Harbor and further east on Bliss Island, L'Etang 

 Head, and Pea Point, and again around the shores of Lepreau Harbor, which is the extreme 

 eastern part of the county. 



The dip of the strata in the St. Andrews Peninsula is uniformly to the south or southeast, 

 at angles from 10° to 25°. ' At an average inclination of 15° over a distance of 5 miles, since 

 the southern margin of the basin is not here reached, the thickness for the beds at this place 

 wiU not be far from 7,000 feet. No well-defined faults or repetitions of the strata are seen in 

 this section. This estimate of thickness far exceeds that hitherto made for any portion of 

 the lower Carboniferous as developed in southern New Brunswick. 



