F L I 



together with water so perfectly, as to form 

 a smooth fluid, of the consistence and co- 

 lour of cream ; if this fluid be left a long 

 time quite tranquil, the flint separates from 

 the cky, and collects in small masses, in 

 a manner analagous to that in which the 

 natu'-al masses occur in the chalk. When 

 flint is first extracted from the quarry it 

 is brittle, has a conchoidal fracture, and 

 feeble lustre ; thin fragments are trans-- 

 lucent. Specific gravity 2*594. According 

 to Klaproth's analysis, it consists of silex 

 98, lime 0'5, alumine 0'25, oxide of iron 

 0'25, water 1. The constant occurrence 

 of flint in the upper chalk, and the ap- 

 parent conversion of animal remains into 

 flint, has given rise to much speculation 

 respecting its origin ; and it was at one 

 time maintained, that flint and chalk were 

 convertible, or capable of undergoing 

 a mutual transmutation. I propose to 

 submit a few observations from the pens 

 of our first writers on this interesting and 

 intricate subject, for after having con- 

 sidered the matter in every point of view ; 

 after having carefully read the opinions of 

 others, and again and again examined 

 strata of flint nodules and tabular flints, 

 flints horizontally and diagonally distri- 

 buted throughout the numerous chalk- 

 pits in the neighbourhood ; after having 

 observed their crushed but not disordered 

 condition, and having commonly found 

 flints imbedded in flints, I am totally 

 unable to arrive at anything approaching 

 to a legitimate deduction. 



" That the beds of chalk and flint were 

 deposited periodically," says Dr. Mantell, 

 "cannot admit of the slightest doubt. Spe- 

 cimens are not unusual, in which angular 

 fragments of black flint, that could not 

 possibly have been originally formed in 

 their present state, are imbedded in chalk. 

 Sir Henry Englefield was the first who 

 directed the attention of geologists to the 

 subject of the shattered condition of the 

 flints found in certain strata. In a paper 

 read before the Linnsean Society, he 

 notices several beds of shattered flints, 

 which occur in a chalk-pit at Carisbrook, 

 in the Isle of Wight ; and, after describing 

 their situation and appearance, proceeds 

 to offer some conjectures upon the pro- 

 bable cause of their destruction. This he 

 supposed might have been occasioned by 

 some sudden shock or convulsion, which 

 in an instant shivered the flints, though 

 their resistance stopped the incipient mo- 

 tion ; for the flints, though crushed, are 

 not displaced, which must have been the 

 case, had the beds slid sensibly. Chal- 

 cedony is often found occupying the 

 hollows of flints, and on this subject it 

 has been remarked that although hi the 

 present compact state of the matter oi 



[ i)7 ] F L I 



flint, it is not easy, though possible, to 

 force a fluid slowly through its pores, yet 

 it is probable that before its consolidation 

 was complete, it was permeable to a fluid 

 whose particles were finer than its own ; 

 and that the particles of chalcedony, 

 whilst yet in a fluid state, being finer than 

 those of common flint, did thus pass 

 through the outer crust to the inner sta- 

 tion they now occupy ; where they also 

 allowed a passage through their own in- 

 terstices to the still purer siliceous matter, 

 which is often crystallized, in the form of 

 quartz, in the centre of the chalcedony, 

 and is so entirely surrounded by it, that 

 it could have no access to its present 

 place, except through the substance of 

 the chalcedony, and the flint enclosing it." 

 In Professor Buckland's Bridgewater 

 Treatise we find the following : " We may 

 in like manner refer the origin of those 

 large quantities of silex, which constitute 

 the chert and flint beds of stratified forma- 

 tions, to the waters of hot springs, holding 

 siliceous earth in solution, and depositing 

 it on exposure to reduced degrees of tem- 

 perature and pressure, as silex is deposited 

 by the hot waters that issue from the 

 geysers of Iceland." Again Dr. Mantell, 

 " the nodular masses of flint are very ir- 

 regular in form, and variable in magni- 

 tude ; some of them scarcely exceeding 

 the size of a bullet, while others are se- 

 veral feet in circumference. Although 

 thickly distributed in horizontal beds and 

 layers, they are never in contact with each 

 other, but every nodule is completely sur- 

 rounded by chalk. Flints so commonly 

 enclose the remains of sponges, alcyonia, 

 and other zoophytes, that some geologists 

 are of opinion that the nucleus of every 

 nodule was originally an organic body, 

 and Townsend states, ' so far as my ob- 

 servation goes, zoophytes appear univer- 

 sally to have formed the nuclei of nodu- 

 lated and coated flints.' The nodules of 

 flint frequently exhibit the internal struc- 

 ture of the enclosed zoophyte most beau- 

 tifully and delicately preserved/' A theory 

 offered by Professor Buckland is to this 

 effect : " It does not appear possible that 

 flints could have been formed by infil- 

 tration into pre-existing cavities, like the 

 regularly disseminated geodes of the trap 

 rocks. Assuming that the mass which is 

 now separated into beds of chalk and flint, 

 was, previously to its consolidation, a 

 compound pulpy fluid, and that the or- 

 ganic bodies now enveloped in the strata 

 were lodged in the matter of the rock, 

 before the separation of its calcareous 

 from its siliceous ingredients, the bodies 

 thus dispersed throughout the mass would 

 afford nuclei, to which the flint, in sepa- 

 rating from the chalk, would, upon the 

 o 



