286 J. W. DAWSON ON THE PHOSPHATES OF CANADA. 



The Acadian or Menevian group, as developed near St. John, 

 New Brunswick, contains layers of calcareous sandstone blackened 

 with phosphatic matter, which can be seen, under the lens, to consist 

 entirely of shells of Lingulce, often entire, and lying close together 

 in the plane of the deposit, of which in some thin layers they appear 

 to constitute the principal part*. Mr. Matthew informs me that 

 these layers belong to the upper part of the formation, and that the 

 1 ayers crowded with Lingulce are thin, none of them exceeding two 

 inches in thickness ; but he thinks that the dark colour of some of 

 the associated sandstones and shales is due to comminuted Lingulce. 



At Kamouraska, where I have studied these deposits, the ordinary 

 phosphatic nodules are of a black colour, appearing brown with blue 

 spots when examined in thin slices with transmitted light. They 

 are of rounded forms, having a glazed but somewhat pitted surface — 

 and are very hard and compact, breaking with glistening surfaces. 

 They occur in thin bands of compact or brecciated limestone, which 

 are very sparingly fossiliferous, holding only a few shells of Hyolithes 

 and certain Scolith its-like cylindrical markings. In some of these 

 beds siliceous pebbles occur with the nodules, rendering it possible 

 that the latter may have been derived from the disintegration of 

 older beds ; but their forms show that they are not themselves 

 pebbles. Phosphatic nodules also occur sparingly in the thick beds 

 of limestone conglomerate which are characteristic of this formation ; 

 they are found both in the included fragments of limestone and in the 

 paste. The conglomerates contain large slabs and boulders of lime- 

 stone rich in Trilobites and Hyolithes; but in these I have not 

 observed phosphatic nodules. 



In some of the limestones the phosphatic bodies present a very 

 different appearance, first noticed by Richardson at Riviere Ouelle, 

 and of which I have found numerous examples at Kamouraska. A 

 specimen now before me is a portion of a band of grey limestone, 

 about four inches in thickness, and imbedded in dark red or purple 

 shale. It is filled with irregular, black, thick- walled, cylindrical 

 tubes, and fragments of such tubes, along with phosphatic nodules 

 — the whole crushed together confusedly, and constituting half of 

 the mass of the rock. The tubes are of various diameters, from a 

 quarter of an inch downward ; and the colour and texture of their 

 walls aro similar to those of the ordinary phosphatic nodules. 



Under the microscope the nodules and the walls of the tubes show 

 no organic structure or lamination, but appear to consist 'of a finely 

 granular paste holding a few grains of sand, a few small fragments 

 of shells without apparent structure, and some small spicular bodies 

 or minute setae. The general colour by transmitted light is brown ; 

 but irregular spots show a bright blue colour, due probably to the 

 presence of phosphate of iron (vivianite). The enclosing limestone 

 and the filling of the tubes present a coarser texture, and appear 

 made up of fragments of limestone and broken shells, with some 

 dark-coloured fibres, probably portions of Zoophytes. Scattered 



* Bailey and Matthew, " Geology of New Brunswick," Geol. Survey Beports. 



