TIIK CARBONIFEROUS. 45 



1st. The Horton Series or Lower Carboniferous Coal-measures, con- 

 sisting of hard sandstones and shales often calcareous, associated 

 with conglomerate and grit, and in some places with highly 

 bituminous shales. They contain underclays and thin coaly 

 seams, remains of plants, fishes, and entomostracans, and foot- 

 prints of batrachians, but no strictly marine remains. This 

 group was first established as a distinct subdivision of the Car- 

 boniferous in Nova Scotia, by Sir C. Lycll and the writer in 

 1844 and 1847. (See Aote 2, p. 99.) 



2d. The Windsor Series or Lower Carboniferous Limestone and 

 Gypsiferous Beds. — This is a marine formation holding charac- 

 teristic shells and corals of the Lower Carboniferous period, 

 and containing in addition to the limestone thick beds of sand- 

 stone, marl, and clay, usually red, and of gypsum. First defined 

 by Sir C. Lyell in 1843. 



3d. The Millstone-grit Series, consisting of sandstones and shales, 

 often red, and conglomei'ate, associated with dark-coloured beds 

 holding fossil plants and Naiadites, and with a few underclays 

 and thin seams of coal. The name Millstone-grit was first 

 applied to these as a distinct group by Mr \\. Brown in 1844. 

 The group was distinctly indicated in Sir W. E. Logan's section 

 of the South Joggins in 1843, and in my paper of the same 

 year on the Lower Carboniferous rocks of Eastern Nova Scotia. 



Above these are (4th) the Middle Coal formation, and (5th) the 

 Upper or Newer Coal formation with the overlying Permo-car- 

 boniferous Series. 



In some localities the lower member is absent, the marine lime- 

 stones resting on the older rocks. In other localities the marine 

 member is absent, or very slenderly developed, and the Lower Carboni- 

 ferous Coal measures and Millstone-grit are united together. In this 

 case, however, the lower series is usually represented by coarse con- 

 glomerates with few fossils. 



The equivalency of these beds with formations abroad is a subject 

 of some importance, more especially with respect to the Horton series 

 or Lower Carboniferous Coal measures, as errors have been com- 

 mitted both in the way of confounding these with the Coal measures 

 above and with the Devonian below ; and in works of general geology 

 very little attention is usually given to them as a distinct group. 

 With regard to the marine limestones, their equivalency to the Lower 

 Carboniferous limestones of other countries is undoubted. The 

 Millstone-grit also admits of very little difference of opinion as to 



r\ 



