768 REPORT—1896. 
is done, however probable the occurrence of rock-basins in Britain may be cons 
sidered to be, their actual existence cannot be accepted as proved. 
When referring to the subject of denudation, mention was made a moment ago 
of the study of the lithological character of the sediments. Admirable work in 
this direction was carried out years ago by one who may be said to have largely 
changed the direction of advance of geology in this country owing to his researches 
‘On the Microscopical Structure of Crystals, indicating the Origin of Minerals and. 
Rocks.” I refer, of course, to Dr. H.C. Sorby. But since our attention has been 
so largely directed to petrology, the study of the igneous and metamorphic rocks 
has been most zealously pursued, whilst that of the sediments has been singularly 
little heeded, with few exceptions, prominent amongst which is the work of 
Mr. Maynard Hutchings, the results of which have been recently published in tho 
‘Geological Magazine,’ though we must all hope that the details which havo 
hitherto been supplied to us, valuable as they are, are only a foretaste of what is 
to follow from the pen of this able observer. Descriptions of the lithological 
changes which occur in a vertical series of sediments, as well as of those which are 
observed when any particular band is traced laterally, will no doubt throw lighs 
upon a number of interesting questions. 
Careful work amongst the ancient sediments, especially those which are of 
organic origin, has strikingly illustrated the general identity of characters, and 
therefore of methods of formation, of deposits laid down on the sea-floors of past 
times and those which are at present in course of construction. Globigerine-oozes 
have been detected at various horizons and in many countries. Professor H: 
Alleyne Nicholson ! has described a pteropod-ooze of Devonian age in the Hamilton 
Limestone of Canada, which is largely composed of the tests of Styliola; and to 
Dr. G. J. Hinde we owe the discovery of a large number of radiolarian cherts of 
Paleozoic and Neozoic ages in various parts of the ylobe. The extreme thinness 
of many argillaceous deposits, which are represented elsewhere by hundreds of feet 
of strata, suggests that some of them, at any rate, may be analogous to the deep- 
sea clays of modern oceans, though in the case of deposits of this nature we must 
depend to a large extent upon negative evidence. The uniformity of character of 
thin marine deposits over wide areas is in itself evidence of their formation at 
some distance from the land; but although the proofs of origin of ancient sedi- 
ments far from coast-lines may be looked upon as permanently established, the 
evidence for their deposition at great depths below the ocean's surface might be 
advantageously increased in the cuse of many of them. The fairly modern sedi- 
ments, containing genera which are still in existence, are more likely to furnish 
satisfactory proofs of a deep-sea origin than are more ancient deposits. Thus the 
existence of Archeopneustes and Cystechinus in the oceanic series of Barbadoes, as 
described by Dr. J. G. Gregory, furnishes strong proofs of the deep-sea character 
of the deposits, whilst the only actual argument in favour of the deep-sea character 
of certain Palaeozoic sediments has been put forward by 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 bas 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, criticised 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 inactive. 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 recognisable in ancient Devonian 
1 Nicholson and Lydekker, Manuai of Palaontology, chap. ii. 
