THE UPPER SILURIAN. 73 



tufaceous rocks, owing to their composition, are much more liable to 

 be rendered crystalline by metamorphism than the ordinary aqueous 

 sediments from which the bases have been leached out by water, and since 

 they are usually not fossiliferous, the appearance is presented of crystal- 

 line non-fossiliferous rocks alternating with others holding abundant 

 organic remains, and comparatively unaltered. The volcanic members 

 of these series are also often very irregular in distribution, and there is 

 little to distinguish them from each other, even when their ages may 

 be very different. These circumstances oppose many difficulties to 

 the classification of all the pre-Devonian rucks of Nova Scotia and 

 New Brunswick, difficulties as yet very imperfectly overcome. My 

 own attempts to unravel these intricacies have as yet been only 

 partially satisfactory to myself, and I have seen quite as little reason 

 to be satisfied with many of the arrangements which have been 

 suggested by others. We shall, however, endeavour to ascertain 

 what new facts are available, and to what extent they contradict or 

 modify the views given in the text of Acadian Geology. 



Messrs Bailey and Matthew have devoted much time and labour 

 to the rocks which crop out from under the Upper Devonian beds at 

 Perry in Maine, and extend thence eastward into New Brunswick, 

 where they have been named the " Mascarene series." I studied 

 these beds in 1862, as they occur at Pigeon Hill and elsewhere near 

 Eastport, and referred them to the Upper Silurian period,* but the 

 tracing of their extension in New Brunswick, and the full e.stabli>h- 

 ment of their age, belongs to the gentlemen above named.-j- 



These rocks are extensively developed in the south-western part 

 of New Brunswick, and their thickness has been estimated at 2000 

 feet. The following section, in ascending order, taken from the 

 Report of the Geological Survey for 1875-6, shows the general 

 structure of the formation in Queen's County. 



Division 1. Gray clay slates, mostly of pale colour and 

 generally somewhat calcareous. Darker- 

 gray clay slates, some of which are carbo- 

 naceous, ..... all. -ut 400 feet. 



Division 2. Black and dark-gray argillaceous or silicious 

 clay slates, with very regular sedimentary 

 bands, about 600 „ 



Division 3. Dark-gray and greenish-gray earthy sand- 

 stones, the lower part compact, the upper 



* Paper on Precarboniferous Flora, 

 f Reports, Geol. Survey, 1875 C. 



