Alfred Bell— Age of the Suffolk Boxstones. 17 



round calcareous shells and fish remains, but the shells have entirely 

 disappeared, and the fish are represented only by the more insoluble 

 portions of their skeleton." "Carbonic acid and ammonia are 

 formed in connection with the decomposition of animal matter." 

 " Phosphate of lime is soluble in water, charged with carbonic acid, 

 and still more so in water containing ammonium carbonate. A solution 

 of ammonium phosphate is thus formed at the expense of the fish 

 bones, and one of calcium carbonate at the expense of the shells. 

 The shells and the fish embedded in the porous sand thus become 

 surrounded by water highly charged with calcium carbonate, or 

 ammonium phosphate. Where these solutions react there is a 

 precipitation of calcium phosphate and some carbonate; in this way 

 tiie loose sand becomes consolidated into a hard nodule." Dr. W. B. 

 Clarke ^ was the first to give any detailed account of the detritus bed. 

 He especially refers to the boxstones as "arenaceous clay nodules 

 that have been rounded by attrition into forms, more or less spherical, 

 upon breaking which a shell, frequently a bivalve, is found in the 

 interior. In some cases the shell itself is preserved, in others 

 nothing but the cast remains". He seems to have anticipated 

 Dr. Credner by saying, "It is not unlikely that the presence of the 

 shell and its molluscous inhabitant, involving certain chemical 

 changes within the mass of clay, may have given rise to the 

 consolidation of the surrounding mass." 



Many phosphatic concretions were dredged by the Challenger off 

 the Cape of Good Hope and elsewhere, where sharks' teeth abounded, 

 as many as 1,500 examples of these being taken in one haul of the 

 dredge. Sharks' teeth abound in the loose sand of the older Red 

 Crag; nearly all the species are recorded from the Continental 

 Oiigocene, while a few survive to the present time. 



In working out the relations of the boxstone fauna to that of other 

 formations I have utilized the lists given by Dr. Harder,' Dr. 1-iavn,' 

 M. Vanden Broeck,* Dr. Nerregaard,^ and by Mr. E. B. Newton, 

 F.G.S.* In making these comparisons I have left out the loose 

 derivative shells found in the lied Crags, but these are all referred to 

 by one or other Continental writers as being of Oiigocene age, and 

 do not affect the conclusions at which I have arrived. 



Harder quotes 93 species from the Oiigocene zones; 21 of these are 

 boxstone species, chieflv Middle Oiigocene (23 per cent approx.). 



Ravn 91 species. Middle and Upper Oiigocene, of which we have 

 36-40 (44 per cent). 



Vanden Broeck 64 species, Middle Oiigocene; Argile de Boom 

 (Upper Rupelien) 22-24 (38 per cent); Lower Rupelien (Berg) 

 62 species, of these I have only found 10 in the boxstones. 



1 "A few remarks upon the Crag of Suffolk" : Ann. Mag. Nat. Hist. (2), 

 yol. viii, p. 205. 



2 Danmarks geologiske Undersegelse, vol. ii, 1913. 



3 K. Danske Vicl. Selsk. Skrift (7), vol. iii, p. 217, 1907. 

 ■* Bull. Soc. Beige de Geologie, vol. vii, p. 78, 1893. 



^ Dansk. Geol. Forening., vol. v, No. 1, 1916. 

 ^ Journal of Conchology, vol. xv, 1916-17. 



DECADE VI. — VOL. V. — NO. I. 



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