148 CARBONIFEROUS. 



fringing or barrier reefs. The nearest land, excepting islands, 

 was probably situated in the north and north-west, for the in- 

 tercalation of shales and sandstones as well as seams of coal in 

 the Lower Carboniferous (Bernician) rocks of Northumberland, 

 suggests that land was not far off, and no doubt, as Dr. A. 

 Geikie has remarked, the Highlands of Scotland rose up 

 above the waters at this epoch. Shallower water conditions, 

 still for the most part marine, prevailed during the deposition 

 of the Yoredale Rocks and the Millstone Grit, and these 

 rocks are intimately connected by similar forms of life ; but 

 in the Coal-measures the conditions became estuarine and 

 terrestrial, or terrestrial interrupted by inundations leaving 

 bands of sandstone and clay, and occasional layers of lime- 

 stone with marine organisms. 



While on the whole the area appears to have been slowly 

 subsiding, yet the Yoredale Rocks did not extend much over 

 the West of England ; indeed, in North Wales the Millstone 

 Grit overlaps them, and rests in places directly on the 

 Carboniferous Limestone. Again, the Coal-measures over- 

 lap the Lower Carboniferous Rocks in parts of the West 

 of England and Wales.^ 



The Carboniferous rocks therefore were mostly formed in 

 the sea and not far from land, and as the remains of 

 terrestrial vegetation occur in them at all horizons, the epoch 

 has sometimes been termed the Phytozoic Period, or Age 

 of Plants. In the Carboniferous rocks we find the earliest 

 traces of Fungi yet known, for their mycelium has been 

 preserved in woody stems of Carboniferous age.^ 



The Ferns, Equisetaceae, and Lycopodiaceae form the most 

 noteworthy plant-remains of this epoch, and they will be 

 noted more in detail further on. The Corals include the 

 genera Lithostrotion and LitJiodendron. The Crinoids include 

 Platycriims and Actinocrimis. Many Polyzoa are met with. 

 Brachiopoda are very abundant, including Spirifera, Orthis 

 and Productus. Lamellibranchiata and Gasteropoda are not 

 uncommon, and we find the latest representatives of the Trilo- 

 bites. Among the Fishes, Megaliditliys is a characteristic 

 Carboniferous genus, and the period has been termed the 

 Megalichthyan by Prof Phillips. Insects and Amphibia (so 

 far as at present known) appear for the first time in this 

 country in the Coal-measures.^ 



' See also A. H. Green, Geol. Yorkshire Coal-field (Geol. Survey), pp. 22-26. 



- W. C. Williamson, Geol. Address, Brit. Assoc. 1883. 



2 There has been no confirmation of the supposed remains of Mammalia noticed 

 by Mr. T. P. Barkas, in his Illustrated Guide to the Fish, Amphibia, etc., of the 

 Northumberland Carboniferous Strata, 1873. 



