TRANSACTIONS OF SECTION C. 769 
coral-reefs in Belgium.! 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 accord- 
ing 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 Carbo- 
niferous Limestone strata of the great western escarpment of the Pennine Chain 
which faces the Eden Valley in the neighbourhood 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 bore-holes 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 the 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 controversy, 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 several parts of the world, but much more information must be 
gathered together before our restorations of ancient sea-margins approximate to 
the truth. The Carboniferous rocks of Britain have been specially studied with 
reference to the distribution of land and water during the period of their accumu- 
lation, and yet we find that owing to the erroneous identification of certain rocks 
of Devonshire as grits or sandstones, which Dr. Hinde has shown to be radiolarian 
cherts, land was supposed to lie at no great distance south of this region in Lower 
Carboniferous times, whereas the probabilities are in favour of the existence of an 
open ocean at a considerable distance from any Jand in that direction. This case 
nr us with an excellent warning against generalisation upon insuflicient 
ata. 
As _a result of detailed study of the strata, the effects of earth-movements 
have been largely made known to us, especially of those comparatively 
local disturbances spoken of as orogenic, which are mainly connected with 
mountain-building, whilst informaticn concerning the more widely spread 
epeirogenic movements is also furnished by a study of the stratified rocks, The 
structure of the Alps, of the North-West Highlands of Scotland, and of the 
uplifted tracts of North America is now familiar to geologists, whilst the study 
of comparatively recent sediments has proved the existence of widespread and 
extensive movements in times which are geologically modern; for instance, the 
deep-water deposits of late Tertiary age found in the West Indies indicate 
the occurrence of considerable uplilt in that region. But a great amount of 
_.' 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. 
