Vol. 56.] ANNIVERSARY ADDRESS OE THE PRESIDENT. lxxiil 



With these four subjects goes of course a great addition to 

 our knowledge of the various local conditions of the formations 

 passed through, as well as of their varying thicknesses. 



So far reference has been made to published information only ; 

 but in continuing these remarks I shall also occasionally have to 

 make some use of unpublished material, whether in the hands of 

 Prof. Boyd Dawkins and of Mr. Etheridge, both of whom I have to 

 thank for information, or in my own. Of course, such unpublished 

 notes are used subject to correction. 



That the Chalk everywhere underlies the Tertiary of the 

 London and Hampshire Basins is a sort of axiom, long taken 

 for granted by all geologists ; but it is nevertheless satisfactory to 

 be able practically to prove it, from the fact that whenever a hole 

 is dug deep enough Chalk is found: for unbelievers in matters 

 geological are not yet extinct. The immense mass of accumulated 

 evidence has long been enough to convince any reasonable being, 

 and we can afford to ignore unreasonable ones, for there are more 

 than 800 wells and borings that pass through Eocene beds to the 

 Chalk in the London Basin. 



It is different, however, when we come to the question of what 

 next underlies the Chalk deep underground ; and it is to this, the 

 underground extension of formations older than the Chalk, that 

 I particularly wish to draw attention, making use not only of 

 borings for water, but of others of a more experimental kind. I 

 hope to be forgiven for omitting references to the many authors who 

 have contributed to our knowledge. 



While we see, from our geological maps, that the Chalk occurs 

 everywhere round the Tertiary beds of the two Basins, and mostly 

 with a broad outcrop, it is not quite the same with the underlying 

 Cretaceous divisions. Though the Upper Greensand and the Gault 

 are now in fair way of being taken as parts of one formation, which 

 it is proposed to call Selbornian, yet in the present case there is 

 some convenience in dealing with the two separately, not using the 

 new classification until the Geological Survey Monograph on the 

 Upper Cretaceous formations is in our hands. First let us deal with 

 the London Basin, including therein the Chalk as well as the 

 Tertiary, and also taking in part of the Wealden tract. 



London Basin (and Weald). 

 The Upper Greensand being, as a rule, comparatively thin at its 

 outcrop and of somewhat varying character, one is not surprised to 



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