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SC/E.VCE-GOSS/r. 



CONlircrEl> BY KliWAKI) 



MAKTIN, V.C: 



Drift Nomenxi.aturk. — It gave me much plea- 

 sure lo see the amount of space devoted to this sub- 

 ject in your issue for April (p. 34S). I hope its 

 perusal will awaken an interest in a rather neglected 

 section of geological science on the part of local 

 obseivers in those districts where Drift deposits occur. 

 It will lead, I trust, to further elucidation of a com- 

 plicated and obscure set of deposits. I gather from 

 Mr. Kennard'.s remarks that he regards the whole of 

 the gravels near Dartford as practically contempora- 

 neous. After comparing them with a very large 

 number of similar deposits in Southern England, and 

 for reasons given in my paper referred to by him, I 

 think that those on Dartford Heath itself are older 

 than those at lower elevations at Milton Street and 

 Galley Hill. After carefully reading Mr. Kennard's 

 remarks, I see no reason to alter my opinion. Unless 

 considerable earth mo\"ements have taken place 

 during the excavation of the Thames Valley, the 

 higher gravels in a given locality, such as the one 

 under consideration, would be the older. I was 

 much struck duiing a study of the gravels of 

 Southern England and the literature relating 

 to them with the fact that all the Pleis- 

 tocene Mammalia came from the set of 

 gravels' most closely connected with the present 

 river system. Many gravel sections occur at higher 

 levels, but have yielded none. An universal negative 

 is, of course, easily refuted by one adverse fact. It 

 is therefore of importance to see if the statement 

 stands the test of future observation, as if true an 

 important datum line is obtained. It was in conse- 

 quence of this, that I could not allow Mr. Kennard's 

 original remarks to remain unchallenged. The 

 gravels occurring at higher levels in the .same 

 localities, than those yielding Pleistocene Mammalia 

 have, as far as I know, only yielded the following 

 evidence as to age. (I.) The Early Drifts near 

 Lenham and above Westenhanger contain blocks of 

 ironstone which yield casts of fossils referred by 

 competent authorities to a Lower Pliocene fauna. 

 The deposits containing them are therefore of later 

 date. .Similar drifts occur in many jjlaccs in the 

 South of England, but have up to the present yielded 

 no fossils. Lilhological evidence and a careful com- 

 parison of levels are our only data. (2.) At Dewlish, 

 Dorsetshire, a distinctly Upper Pliocene fossil, 

 Ekphas meridioiialis, has been found in a drift, 

 in a deposit, situated at a lower level than the 

 High Level or Early Drift of that district, and 

 above the river terraces. It is thus seen that, 

 although the evidence is admittedly slender, it 

 distinctly pf>inls to the possibility, if not indeed 

 the probability, of the intermediate series of drifts, 

 termed Lower Plateau Drifts, being of Pliocene 

 age. Here the local observer might unearlh valuable 

 evidence. Mr. Kennard finds fault with the names 

 u.sed l>y me lo designate the broad divisions of these 

 drift deposits, but I have merely adapted those pre- 

 viously u.sed by the Geological Survey, and some of 

 the authorities he quotes. The term " Early Drift " 

 is defined by me in a previous paper, " Pebbly 



Gravel friim Goring Gap to the Norfolk Coast " 

 (Proc. Geo. Assoc, Vol. xiv. , pp. 3S9 to 404), and the 

 term " Glacial" is also there explained. It would be 

 an easy task to show that the terms suggested by him 

 are far from being above reproach, but it woiUd take 

 far too much of vour \aluable space. The fact is, 

 that a great deal of work must be done fiefore we can 

 definitely, and with some approach to nialhenialical 

 precision, correctly classify and name these obscure 

 deposits. In conclusion, I may state that the object 

 I had in view in writing the paper referred to, was to 

 describe the gravels at greater heights O. D. than 

 those on the river terraces, and these latter are taken 

 only as a kind of base line. — --/. E. Siillcr, 14, 

 Aiiieyshani Road, New Cross, S.E., April, 1899. 



Work ok thk Ouse. — Under the above heading, 

 in the " Annual Report of the Vorkshire Philosophical 

 Society "' for 1S9S, issued a few da\'s ago, Mr. PI. M. 

 Platnauer, B. Sc, gives the results of some observations 

 he has been making with regard to tlie amount of 

 material brought past Vork, In- the waters of the 

 Ouse. As these have some bearing upon a n(.)lc 011 

 the "Origin of the Humber Mud," published in 

 Science-Gossip, Vol. v. p. 7, a summary of Mr. 

 Platnauer's observations may not be out of place. 

 The method of procedure was very simple : 102 

 difierent samples were taken from the River ( )use, and 

 a litre of each evaporated to complete drj'ness. The 

 residue thus obtained was carefully weighed. An 

 estimate of the quantity of water passing a given 

 point in a given time was then obtained, and a short 

 calculation gave the amount of solid matter -passing 

 ^'ork in any given period. Mr. Platnauer estimates 

 that, taking everything into consideration, about 

 300,000 tons of material are annually carried past the 

 City of ^'ork, in the waters of the Ouse. Unfortu- 

 nately, no attempt has been made lo dift'erentiate 

 between the amount of solid matter in solution and 

 that in suspen.sion ; though, we are promised, experi- 

 ments on these lines will be .shortly Cdnducted. What 

 at first seems remarkable, however, is, that when the 

 water is swollen with Hood, and, consequently, 

 turbid, there is less solid matter per litre 

 after evaporation than when the water is 

 clear, and flowing under ordinary condi- 

 tions. This is no doubt accounted for by .Mr. 

 Platnauer, who rightly states that in the former 

 instance the water is principally surface water, whilst 

 in the latter it has passed through the soil and rock, 

 and reached the Ouse b)' means of springs. It is 

 then consequently charged with much mineral matter. 

 If, therefore, during a " fresh," when the water is full 

 of numerous fine jiarticles in suspension, there is less 

 .solid matter per litre than when the stream is normal 

 and clear, it is evident only a small proportion of the 

 300,000 tons annually swept pa.st ^'ork is in suspen- 

 sion. Of course it is not forgntlen that when the 

 river is in llooil a far giealer (juantity of water, and 

 conse(|uently solid matter, passes ^'ork in a day than 

 when the water is low. iJut the period of llimd is iioi 

 a long one. It is also very probable a large propor- 

 tion of this matter in suspension never reaches the 

 Humber, but it is deposited on the alluvial flats, as 

 shown in the article in .SciENCE-GossM' for June, 

 I.S9S, already referred lo. Now, with regard to ihe 

 bearing of Mr. Platnauer's notes on the origin of ihe 

 Humber mud, his observatiniis conclusively show thai, 

 conparatively speaking, there is no extraordinary 

 amoimt of suspended material brought past \'ork, 

 and prcibably a much less volume gets inio the 

 estuary. I say "comparaiively .speaking" advisedly, 

 as only those who are ac(juainted with the 

 vast accumulations i>f imuls and sill, usually of 



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