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Now the problem which soon suggests itself to the observer 

 iSj — Were the flints formed contemporaneously with the deposition 

 of the chalk, or have tbey been formed since its consolidation ? 

 And further, if formed after the cbalk was consolidated, how long 

 after ? Had the chalk been elevated and become dry land when 

 they were formed or did this segregation of the silica take place 

 when it was a more or less compact ooze still at the bottom of 

 the sea ? 



Let us see then what evidence is furnished to us on this 

 question by observation of the modes in which it occur. For 

 convenience we will take the last division first. 



True Vein Coueses. — In the upper portion of the chalk 

 clifFs and quarries, both east and west of the town, narrow veins 

 of flint may be seen running through the chalk, especially where 

 the chalk is in what may be termed a rubbly state. My own ob- 

 servation shows that these narrow oblique veins of flint are more 

 often met with near the surface than at great depths. 



There can be little doubt that this flint has been deposited 

 since the consolidation of the chalk, in all probability since it has 

 been uplifted and become dry land, or perhaps it might have 

 been during the long slow process of the uplifting of the chalk. 

 Water holding silica in solution has no doubt been the agent. 



2. Layers op Nodular Flints and Thick Tabular Sheets. 

 — Seeing that the flint of the veins just considered has un- 

 doubtedly been deposited since the solidification of the chalk 

 why not it may be asked the nodules, &c. ? 



There seem to be many difiiculties in the way of such an ex- 

 planation of their origin. The hollow flints must have had a 

 coating of silica formed round the sponge, which in so many 

 cases is the origin of their form, before the decay or disintegra- 

 tion of the delicate framework and tissues of the sponge skeleton. 

 The wood, whose finest fibre and structure is preserved, had no 

 time to decay before it underwent " a sea change into something 

 new and strange " and became the beautiful mass of chalcedony 

 to which we have before referred. Dr. Hinde in his " Fossil 

 Sponge Spicules from the Upper Chalk," speaks of a quantity of 

 flint-meal, as it is termed, the greyish powder we have 

 before spoken of, in the interior of a large spherical 

 nodule, and says respecting it : " Without entering here into the 

 J vexed question about the formation of the flints in the chalk, it 

 B may be as well to notice that the beautifully perfect state of 

 Hk preservation of the various delicate fossil organisms in the interior 

 ^H^of this flint, when compared with the nearly complete obliteration 



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