126 Notices of Memoirs — Brief Notices. 



calcareous. These are seen 'hj their faunas, as shown at Arisaig, etc., 

 to range from the Llandoveiy to the Ludlow or higher. A peculiar 

 phase of this formation is the plant-hearing beds near St. John, N.B., 

 which contain many types of plants that reappeared in the Carboni- 

 ferous, with others that are special to this locality. 



Following this formation there is a break in the succession, the 

 Middle Devonian being absent, or at least not recognized by its marine 

 fossils, and the next formation (Upper Devonian) by its plant remains 

 shows a close relation with the Lower Carboniferous, yet it has many 

 typical Devonian genera and species of plants. The Carboniferous 

 Age began with a widely extended deposit of marine Limestones 

 spreading through nearly the whole length of the eastern provinces 

 in a belt across their centre, but not known in their northern part. 

 The Millstone Grit and Coal-measures followed in a widely extended 

 tract to and under the Gulf of St. Lawrence. In a northerly direction 

 they were covered by the Permo-Carboniferous found along the borders 

 of the gulf and extending into the province of Prince Edward's Island. 



The final geological system of this part of Canada was the Trias (or 

 Jura-Trias), which occupied a large area in the Bay of Fundy and 

 the Basin of Mines, and is also found in the islands of the Gulf of 

 St. Lawrence. In the Bay of Pundy area and the Basin of Mines the 

 system is characterized by extensive eruptions of dolerite and volcanic- 

 ash deposits that have left a strong imprint on the topography of the 

 country as it now appears. Subsequent to the Jura-Trias there were 

 no great geological systems laid down in this region, and it is supposed 

 that it remained for long ages above the sea. Only in post-Pliocene 

 time did the sea again invade these provinces, and lay clown a marine 

 fauna closely related to and mostly of species living at the present time. 



II. — Bkief Notices. 



rLXJOESPAii. — An important paper on "The Fluorspar Deposits of 

 Derbyshire " has been contributed by Mr. C. B. Wedd, F.G.S., and 

 Mr. G. Cooper Drabble to the Transactions of the Institution of Mining 

 Engineers (1908, vol. xxxv, pp. 501, etc.). The authors give a general 

 account of the structure of the Carboniferous Limestone area and of the 

 associated igneous rocks. The limestone is from 1,500 to 1,700 feet 

 thick, and forms the southern end of the Pennine anticline. The 

 fluorspar appears to be confined to the upper 600 feet of the limestone, 

 and is chiefly concentrated within 300 or 400 feet of the top. The 

 upper beds of the limestone contain a good deal of chert, also secondary 

 quartz ; they are often dolomitic, are more fossiliferous than the lower 

 strata, and contain bituminous products. Moreover, all the known 

 sheets of igneous rock are found in the upper half of the great mass of 

 Derbyshire Limestone. The mineral deposits occur in joints and 

 cracks, in pockets and pipes, and in independent 'flats'. The fluor- 

 spar is remarkably free from silica ; 1 per cent, is an exceptional 

 quantity. The authors believe that local circumstances agree best 

 with the hypothesis of deposition in fissures and to a small extent as 

 a metasomatic replacement of the country-rock, from a heated aqueous 

 solution containing gases and forced up from a great depth, possibly in 



