ANNIVERSARY ADDRESS OF THE PRESIDENT. IxXV 



which no forms of a more composite structure than Fucoids have yet 

 been detected. These bottom rocks and the superposed Lower Silu- 

 rians of that tract were, it appears, elevated into dry land, and placed 

 during a long period out of the reach of sedimentary influence, since 

 none of those strata of the unequivocal Upper Silurian of Bohemia, 

 or the Lower and Middle Devonian, which are so much developed in 

 the Hartz, are to be seen in the Thiiringerwald. 



Towards the close, however, of the Devonian era, both tracts were 

 again covered by a sea in which animals lived differing from all 

 those which preceded them, whilst the recesses of that ocean, whether 

 in this region or in the Rhenish provinces, were spread over by vol- 

 canic dejections which were interlaminated with ordinary submarine 

 beds. These were followed by other accumulations of mud and sand, 

 in which thin courses of coal were formed out of the transported 

 stems, branches, and leaves of land-plants. 



After these lower carboniferous beds had been accumulated, a great 

 upheaval took place over all those parts of Germany and France 

 where such strata occur, raising them up with those which had pre- 

 ceded them. The next sediments formed on the edges of all that 

 preceded them are the feeble equivalents of our upper coal-fields, 

 and these were succeeded by the rothe-todte-liegende or lower red 

 sandstone. And here the authors observe that our country offers no 

 example of that great break between the lower and upper divisions 

 of the carboniferous group which is so very dominant a physical 

 feature throughout Germany and France. 



It was after the deposition of the lower red sandstone that one of 

 the most striking of the physical revolutions of this portion of the crust 

 of the earth took place in the change of the geographical direction 

 of the masses of rock, from their normal alinement of N.E. and S.W. 

 to one trending from N.W. to S.E., the turbulence of the period being 

 decisively marked by great outbursts of porphyry and the extravasa- 

 tion of vast sheets of porphyritic lava. 



The authors then observe that it is evident from the disturbed 

 condition of the secondary strata between the Thiiringerwald and 

 the Hartz, as well as from similar appearances to the north of the 

 Hartz, that each of these older masses was for a long period an 

 area of upheaval and oscillation, by which the interjacent forma- 

 tions were thrown into the plicated forms which they still exhibit. 

 The authors further infer that there are in the Thiiringerwald 

 proofs of ancient movements of which no trace is to be found in the 

 Hartz, thus affording evidence of the truly local character of such 

 disruptions. 



It is also observed, that, while each of these tracts presents some 

 marked analogies with the Silurian basin of Bohemia, each differs 

 more from that tract than they do from each other. In their great 

 fundamental rocks of greenish and talcose grauwacke, the South 

 Thiiringerwald and the district of Prague agree, as well as in the 

 chief mass of the Lower Silurian rocks, though the fossils of the 

 primordial zone of Bohemia have not been found in the Thiiringer- 

 wald, and all the Lower Silurian is wanting in the Hartz ; and the 



