436 



THE GEOLOGIST. 



been for some years endeavouring to establish as to the true position of the 

 Caithness flags with their numerous ichthyolites seems to be admitted by my 

 contemporaries. The lamented Hugh Miller considered these ichthyolites 

 as belonging to the lower member of the group, and had good grounds for his 

 views, since at his native place, Cromarty, these fish-beds appear very near the 

 base. But, by following them into Caithness and the Orkneys, I have shown 

 that they occupy a middle position, whilst the true base of the group is the 

 equivalent of the zone with Cephalaspis, Pteraspis, and Pterygotus. 



And here it is right to state, that the Upper Silurian rocks which are clearly 

 represented in Edinburghshire, and which in Lanarkshire seem to graduate 

 upwards into the Lower Old Red or Cephalaspis sandstone, are wanting in the 

 Highlands ; thus accounting for the great break which there occurs between 

 the crystallized rocks of Lower Silurian age and the bottom beds of the Old 

 Red Sandstone. 



Of the Old Red Sandstone of Scotland and Herefordshire I may be permitted 

 further to observe, that its downward passage into the uppermost Silurian 

 rock, and the upward passage of its higher strata into the Carboniferous strata, 

 has been well developed, the one near Ludlow, chiefly through the labours of 

 Mr. Lightbody ; the other in Scotland, through the researches of the Govern- 

 ment Geologists, Howell and Geikie, as well as by those of Mr. D. Page, and 

 other observers. On this head I may, however, note, what my contemporaries 

 seem now to admit, that the removal of the Caithness flags and their numerous 

 included ichthyolites from the bottom of this group, and their translation to 

 the central part of the system, as first proposed by myself, is correct. In 

 truth, the lower member of this system is now unequivocally proved to be the 

 band with Cephalaspis, Pteraspis, &c, as seen in Scotland, England, and 

 Russia. The great break which has been traced in the south of Scotland by 

 Mr. Geikie between the lower and upper Old Red, is thus in perfect harmony 

 with the zoological fact that the central or Caithness fauna is entirely wanting 

 in that region, as in England — as it is indeed in Ireland, where a similar break 

 occurs. 



It gratifies me to add that many new forms of those fossil fishes which so 

 eculiarly characterize the Old Red Sandstone, have been admirably described 

 y Sir Philip de Grey Egerton in the "Memoirs of the Geological Survey," and 

 I must remark that it is most fortunate that the eminent Agassiz is here so well 

 represented by my distinguished friend, who stands unquestionably at the 

 head of the fossil ichthyologists of our country. 



Very considerable advances have been made in the development of our ac- 

 quaintance with that system — the Carboniferous— which in the North of England 

 — Yorkshire — has been so well described by Professor Phillips, and with which 

 all practical geologists in and around Manchester are necessarily most interested. 

 The close researches of Mr. Binney, who has, from time to time, thrown new 

 lights on the origin and relations of coal, and the component parts of its matrix, 

 established proofs so long ago as 1840, that great part of our coal-fields was 

 accumulated under marine conditions ; the fossils associated with the coal-beds 

 being, not as had been too generally supposed, of fluviatile or lacustrine cha- 

 racter, but the spoils of marine life. Professor Henry Rogers came to the same 

 conclusion with regard to the Appalachian coal-fields in America, in 1842. 

 Mr. Binney believes that the plant Sigillaria grew in salt water, and it is to be 

 remarked that even in the so-called " fresh-water limestones" of Ardwick and 

 Lc Botwood, the Spirorbis and other marine shells are frequent, whilst many of 

 the shells termed Cvpris may prove to be species of Cythere. Again, in the 

 illustrations of the fossils which occur in the bands of iron ore in the South 

 V\ elsh coal-field, Mr. Salter, entering particularly into this question, has shown 

 that in the so-called " Unio beds" there constantly occurs a shell related to the 

 -\ha of our coasts, which he terms Anthracomya; whilst, as he has stated in 



