16 On the Foi-mation of the Flints of the Uppet- Chalk. 



tent and during a certain part of the chalk formation only, dif- 

 fering, as is known, in different localities, could only form itself 

 into masses which occupy a certain space. Whether it took the 

 form of nodular or tabular masses was owing to local modifying 

 causes. Where organic remains of any considerable size, or 

 grouped in particular masses, happened to be abundant and lie 

 near one another, they acted as separate centres, while the solu- 

 tion was attracted to them in a mass. Hence the fantastic and 

 varied forms in which we find the nodules, together with the 

 projecting bodies, the supply of material being often too limited 

 to encase the whole of all the organic bodies by which it was 

 attracted. Where those bodies were less abundant or less indi- 

 viduahzed, — as where there was a layer of minute organic bodies, 

 — there would be fewer centres of attraction, and tabular flints 

 would be formed. Wherever the concretions happened to form 

 themselves they would be attracted by and envelope, more or 

 less, every organic body with which they came in contact, living 

 or dead. That the siliceous liquid possessed the power of pene- 

 trating, — that is, had some peculiar affinity for, — the substance of 

 the organic bodies, vegetable or animal, which it enveloped, and 

 even sometimes without being in sufficient quantity to envelope 

 them at all, is a fact which we see before us. This may be a fact 

 difficult to explain, but it is one which is exemplified in innu- 

 merable other instances, and which is not therefore peculiar to 

 flint*. 



Such are the conclusions to which a very careful and extensive 

 observation of the phsenomena of flints has led me. Accepting 

 the views of Dr. Turner, combined with the well-known facts of 

 the products of thermal springs, as affording a satisfactory and 

 the most probable explanation of the origin of the siliceous liquid, 

 I offer these conclusions as explanatory of the modes and forms 

 in which we actually find the flints themselves : and I offer them 

 without being wedded to any preconceived notion or theory, but 

 simply as the results of extensive observation, and as alone ap- 

 pearing consistent with all the varied class of facts which that 

 observation has brought under my notice. 



Highgate, Nov. 1846. 



• The extreme liquidity of the siliceous fluid, combined with its specific 

 gravity and the superincumbent pressure, help to explain these facts. The 

 questions of that specific gravity of the siliceous fluid, and of its not under- 

 going any material contraction when solidified, cannot be here discussed, 

 though illustrating and supporting the conclusions to which other facts have 

 above led. 



