

Professor J. E. Marr — Address. 471 



presently have more to say with regard to work connected with the 

 lithological characters of the sediments. Whilst mentioning glacial 

 denudation, let me allude to a piece of work which should be done in 

 great detail, though it is not, strictly speaking, connected with strati- 

 graphy, namely, the mapping of the rocks around asserted " rock-basins." 

 I can find no actual proof of the occurrence of sach basins in Britain, 

 and it is very desirable that the solid rocks and the drift should be care- 

 fully inserted on large-scale maps, not only all around the shores of 

 several lakes, but also between the lakes and the sea, in order to ascertain 

 whether the lakes are really held in rock-basins. Until this work is done, 

 however probable the occurrence of rock-basins in Britain may be con- 

 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 the Geological Magazine, though we must all hope that the 

 details which have 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. 

 Desolations 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 light 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 Palaeozoic 

 and Neozoic ages in various parts of the globe. 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 sediments 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 

 case of many of them. The fairly modern sediments, 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 Archceopneustes and Cystechiiius in the oceanic series of Barbadoes, as 

 described by Dr. J. W. 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 



1 Nicholson and Lyddkker, " Manual of Palaeontology," chap. ii. 



