ANNIVERSARY ADDRESS OF THE PRESIDENT. U 



with trappean rocks, in their turn resting upon a mass of black slates, 

 which cover other sandstones and conglomerates well-seen in the 

 vicinity of Bangor. Still lower rocks are found in Anglesea, chiefly 

 micaceous and chloritic slates, mixed occasionally with quartz rocks, 

 of which those forming the Holyhead mountain afford excellent ex- 

 amples, with here and there also some calcareous matter, even form- 

 ing limestone. 



Having received a letter from Professor Naumann of Leipsic 

 respecting certain sandstones and schistose clays of the environs of 

 Oschatz, referring these rocks to the Permian system. Sir Roderick 

 Murchison communicated this letter to the Society, with a few re- 

 marks recalling your attention to the reasons which had induced 

 him to assign the name of Permian to the accumulation of deposits 

 of which the roth-liegende of German geologists forms the base, and 

 which also includes their zechstein and kupferschiefer. Professor 

 Naumann mentions the discovery in these deposits of Calamites gigas, 

 a fern allied to Sphenopteris erosa, and many plants differing from 

 those of the coal-measures, and stated that many of the ichthyolites 

 are similar to the Palseoniscus or Amblypteris, and to the Xena- 

 canthus of Bey rich. The general mineral aspect of the lower beds, 

 white sandstone and greyish schists, referred to the roth-liegende, 

 and about 800 feet thick, is stated to resemble that of the coal- 

 measures, above which come (1) quartziferous porphyry, (2) red 

 sandstones, (3) zechstein (30 to 60 feet thick only), and (4) red 

 and mottled clays. 



Although generally in the British islands we have so much evi- 

 dence of a great disturbance of deposits, after those to which we 

 have given the name of coal-measures, so that the various beds of the 

 new red sandstone series of English geologists are discovered resting 

 unconformably upon such portions of these older rocks as may have 

 been beneath the waters in which the newer accumulations were 

 effected, we should expect to find beyond the area so disturbed, evi- 

 dence as to a passage of the one series into the other. Moreover we 

 are not to suppose the ocean blotted out from the face of the globe, 

 while deposits, marking the growth of plants over great areas, were 

 taking place in apparently fresh waters during our coal-measure 

 period. We have to expect also equivalent accumulations in equal 

 geological time entirely marine, from equivalents inclusive of the 

 carboniferous limestone, which of course need not contain a limestone 

 bed in them where there was no supply of calcareous matter from the 

 harder parts of marine animals or from springs, to equivalents of the 

 oolitic series of western Europe inclusive, and which may also have 

 been formed in certain regions under totally different conditions. 



By regarding deposits on the great scale, particularly when land 

 plants that may have grown upon the beds above which their re- 

 mains now form coal, or that may only have been drifted moderate 

 distances, are concerned, and thus a fair admixture of land and water 

 he inferred, we shall eventually arrive at real equivalents in geological 

 time, and at the desirableness of particular groups and divisions in 

 geological accumulations. It is interesting to consider that within 



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