Notices of Memoirs — Geological Cycles in Canada. 125 



In the section at Aston Rowant,^ Oxon, a compact yellowish limestone 

 band 1 foot in thickness marks the upper limit of the zone, and here 

 we measured 19 feet for the thickness of the zone. At Hart's Lock 

 Wood,^ near Whitchurch, Oxon, a band of yellowish lumpy and 

 nodular chalk (hard and soft mixed), much less compact than at 

 Aston Rowant, is developed at the top of the zone, but this to 

 a thickness of 3 feet, and at this place the thickness of the zone is 

 24 feet. In the present section, where there is no definite rock 

 development at the top of the zone, the thickness, as already stated, 

 is 32 feet. We can therefore surmise that the development of a hard 

 rock band at this horizon indicates a period of arrested or diminished 

 sedimentation, and in connection with this it is interesting to note 

 that in this section, where no rock bed is present, the transition 

 between the upper Holaster plantis-zone type of Micraster with 

 moderately inflated * areas ' to the definite M. cortestudinarium-zoiiQ 

 type with strongly inflated ' areas ' occupies a more extensive 

 vertical range. 



isroTZOES o:f :M:E:]yEOii?,s. 



I. — Geological Cycles in the Maritime Pkovinces of Canada. By 

 G. F. Matthew, D.Sc, LL.D. Trans. Roy. Soc. Canada, 1908-9, 

 ser. Ill, sect, iv, vol. ii, pp. 121-43. 



THE object of this paper is to show briefly the succession and age 

 of the several formations that were accumulated in the eastern 

 provinces of Canada, from the earliest that can be recognized to the 

 end of the Trias (or Jura-Trias). 



As the Cambrian is well represented in these provinces by a formation 

 that contains many characteristic faunas, it forms a basis to which the 

 older and later formations can be co-related. The writer upon this 

 basis affirms the presence of several formations, or systems, older than 

 the Cambrian, and indicates the physical characteristic by which they 

 are separable from each other (there being no fossils in these earlier 

 groups of strata by which they can be distinguished). One of these 

 groups is the gold-bearing or Maguma series of Nova Scotia, having 

 the enormous thickness of 5 miles of sandstones (quartzites) and 

 slates, the chief gold-bearing zone being near the middle of the 

 succession. Older than this is a group containing much limestone, 

 which the author compares to the Grenville Limestones of the 

 Laurentian system. Younger than the Maguma series, but older than 

 the Cambrian, are other groups of strata, many of which consist 

 largely of effusive rocks. 



Above the Cambrian (which includes also the Lower Ordovician) 

 there is a break in the succession ; the Upper Ordovician is wanting, 

 and the Upper Silurian begins in many districts with effusive rocks 

 and elsewhere with sandstones ; these are succeeded by fine dark-grey 

 shales, and these by paler shales and sandstones, which are also more 



1 Mem. Geol. Surv. (Expl. Sheet 254), Henley-on-Thames, 1908, pp. 39, 40. 

 » Proc. Geol. Assoc, 1908, vol. xx, p. 396. 



