472 Reports and Proceedings — 



Professor Suess. who notes the similarity of certain structures of creatures 

 in ancient rocks to those possessed by modern deep-sea Crustacea, 



especially the co-existence of trilobites which are blind with those which 

 have enormously developed eyes. 



A question which has been very prominently brought to the fore in 

 recent years is that of the mode of formation of certain coral-reefs. The 

 theory of Charles Darwin, lately so widely accepted as an explanation of 

 the mode of formation of barrier-reefs and atolls, has been, as is well 

 known, criticized by Dr. Murray, with the result that a large number of 

 valuable observations have been recently made on modern reefs, especially 

 by biologists, as a contribution to the study of reef formation. Nor have 

 geologists been iuactive. Dr. E. Mojsisovics and Professor Dupont, to 

 mention two prominent observers, have described knoll-like masses of 

 limestone more or less analogous, as regards structure, to modern coral- 

 reefs. They consider that these have been formed by corals, and, indeed, 

 Dupont maintains that the atoll-shape is still recognizable in ancient 

 Devonian coral-reefs in Belgium. 1 I would observe that all cases of 

 " knoll-reefs " of this character have been described in districts which 

 furnish proofs of having been subjected to considerable orogenic 

 disturbance, subsequent to the formation of the rocks composing the 

 knoll-shaped masses, whilst in areas which have not been affected by 

 violent earth foldings, the reef-building corals, so far as I have been able 

 to ascertain, give rise to sheet-like masses, such as should be produced 

 according to Dr. Murray's theory. I would mention especially the reefs of 

 the Corallian rocks of England, and also some admirable examples seen 

 amongst the Carboniferous Limestone strata of the great western escarp- 

 ment of the Pennine Chain which faces the Eden Valley in the neighbour- 

 hood of Melmerby in Cumberland. Considering the number of dissected 

 coral-reefs which exist amongst the strata of the earth's crust, and the 

 striking way in which their structure is often displayed, it is rather 

 remarkable that comparatively little attention has been paid to them by 

 geologists in general, when the subject has been so prominently brought 

 before the scientific world, for we must surely admit that we are much 

 more likely to gain important information, shedding light upon the 

 methods of reef-formation, by a study of such dissected reefs, than by 

 making a few boreholes on some special coral island. I would specially 

 recommend geologists to make a detailed study of the British coral-reefs of 

 Silurian, Devonian, Carboniferous, and Jurassic ages. 



Turning now to organic deposits of vegetable origin, we must, as a result 

 of detailed work, be prepared to admit the inapplicability of any one theory 

 of the formation of coal-seams. The " growth -in-place " theory may be 

 considered fairly well established for some coals, such as the spore-coals, 

 whilst the " drift " theory furnishes an equally satisfactory explanation of 

 the formation of cannel-coal. It is now clear that the application of the 

 general term coal to a number of materials of diverse nature, and probably 

 of diverse origin, was largely responsible for the dragging-out of a contro- 

 versy in which the champions of either side endeavoured to explain the 

 origin of all coal in one particular way. 



The stratigraphical geologist, attempting to restore the physical 

 geography of former periods, naturally pays much attention to the 

 positions of ancient coast-lines ; indeed, all teachers find it impossible to 

 give an intelligible account of the stratified rocks without some reference 

 to the distribution of land and sea at the time of their formation. The 

 general position of land-masses at various times has been ascertained in 



1 Similar knoll-like masses have been described in this country by Mr. R. H. 

 Tiddeman, as occurring in the Craven district of Yorkshire, but he does not attribute 

 their formation to coral-growth to any great extent. 



