2 34 



SCIENCE- G OSSIP. 



the facts at present observed ; but one is naturally 

 shy of theory, especially as applied to such an 

 obscure formation. That the denudation must 

 have been very severe is shown by its enormous 

 extent. 



The relation of this to the other Pleistocene de- 

 posits of the area at present under consideration 

 may be briefly indicated thus : — 



West Witterixi 

 Rabble-drift. 



Selsey. 

 Rubble-drift. 



BRIGHTON. 



Rubble-drift. 



Marine shingle (traces). Marine shingle. Marine shingle 

 Estuarine clay. Estnarine clay. and sand, 



Fluviatile beds, with Marine sand. with derived 



derived erratics. 



Erratic Deposit. 



erratics. 



As pointed out by Mr. Reid, who discovered it, the 

 " erratic deposit " is clearly the equivalent of the 

 chalky boulder-clay of the Thames Basin, which 

 we know to be older than the Palaeolithic river- 

 terraces. If, then, the rubble-drift can be shown 

 to be contemporaneous with these river -terraces, or 

 with one of them, then we shall be able to correlate 

 the Pleistocene subdivisions of the Hants Basin 

 with those of the Thames. 



It would be strange indeed if a deposit of the 

 nature of rubble-drift, while so extensively de- 

 veloped in the Hants Basin, were yet unrepresented 

 in that of the Thames — if the subaerial agencies 

 that operated on so large a scale on the South 

 Downs had left the North Downs untouched. 

 Rubble-drift, however, does occur in the Thames 

 Basin. In the dry chalk valleys of the North 

 Downs we find a deposit which is identical with 

 the typical rubble-drift of the Hants Basin, and 

 which occupies a similar position as far as it ex- 

 tends. It is true that it is mapped as river-gravel, 

 but there are very serious objections to its being- 

 classed as such, and in some instances, as in the 

 case of the Carshalton mass, no river could have 

 existed in the position in wdrich the deposit is 

 found. It may be urged that the insignificant 

 masses of rubble-drift in the North Downs cannot 

 be safely correlated with the extensive sheets 

 which project from the South Downs, but this 

 objection is readily answered when we come to 

 examine the Palaeolithic drift of the valley of the 

 Wandle. 



The Palaeolithic deposits of the Wandle Valley 

 were described by me in the August number of 

 Science-Gossip (ante, p. 69). They occur in two 

 terraces, the lower one of which not only occu- 

 pies the river valley but also extends into the dry 

 chalk valleys of the North Downs. This lower 

 mass may be divided into two contemporaneous 

 sections— viz. (a) the angular detritus of the 

 chalk area, which comprises the dry valleys and 

 coombes ; and (b) the subangular gravel of the 

 Eocene tract, or river-vallej r . The former is 

 typical rubble-drift, and passes sideways into the 

 latter, which is a true river-gravel. I have no 

 doubt that a similar state of affairs will be found 



in those other tributary valleys of the Thames 

 that extend into the chalk hills, and I know 

 from personal observation that it is the case 

 with the valley of the Ravensbourne. If then 

 we accept the correlation of the rubble-drift of 

 the North with that of the South Downs, and 

 it would be unreasonable not to do so, then 

 the contemporaneity of the rubble-drift of the 

 Hants Basin with the newer Palaeolithic gravels of 

 the Thames is established. The reason why the 

 rubble-drift has retained the character of a suh- 

 aerial drift throughout the whole of that part of 

 the Hants Basin which we have been considering, 

 and yet has mostly taken the form of a river-gravel 

 in the Thames Basin, is that in the former area 

 the rubble-drift had only a level plain, left by 

 marine denudation, with a few small streams to 

 overwhelm ; but that in the latter tract it had to 

 cope with a well-developed river-system, so that 

 directly it left the dry chalk valleys it was con- 

 verted into river-gravel. 



The relation of the Pleistocene deposits of the 

 two areas may be briefly indicated thus : — 



Hants Basin. 



= Rubble-drift. 



Fluviatile, estuarine, and 

 marine deposits. 

 = ' Selsey erratics. 



Thames Basin. 



Newer Palaeolithic terrace 

 Older Palaeolithic terrace 



Chalky boulder-clay 



150 High Street, Sutton, Surrey. 



The completion of the great catalogue of books 

 at the British Museum, after twenty years' labour, 

 is an important event. This index is contained in 

 upwards of six hundred volumes, and enumerates 

 the titles of no less than two million books. The 

 staff is now to be occupied in constructing the 

 subject index, which it is estimated will require 

 fifteen years to complete. 



Mr. Henry Spence. Hon. Secretary of the 

 Birkbeck Natural History Society, sends us a copy 

 of its fourth annual report, and the Committee 

 desires us to call the attention of those interested 

 in the subject to this society. Its meetings are 

 monthly, and are held at the Birkbeck Institute. 

 Bream's Buildings, London, W.C., where the Hon. 

 Secretary may be addressed. There are also 

 monthly excursions conducted by various members 

 with local knowledge. Visitors are invited to com- 

 municate with Mr. Spence. 



Discontinuous Distribution. — In the "Ameri- 

 can Naturalist" for November Professor W. M. 

 Wheeler records a notable instance of " discon- 

 tinuous distribution." In 1886 a remarkable and 

 aberrant arachnid was reported from Sicily under 

 the name of Koenenia mirabilis. Although repre- 

 senting a distinct group it had a superficial re- 

 semblance to the whip scorpions. In the spring 

 of 1900 Professor Wheeler obtained in Texas an 

 arachnid specifically identical with the Sicilian 

 form. Professor Wheeler maintains from various 

 evidence that the Koenenia was not introduced, 

 and he regards it as a survival of an ancient fauna. 

 It may be remembered that a similar case occurs 

 in Procapyx stylifer, a primitive thysanurid insect, 

 in Liberia and Argentina. 



