VIl] DIATOMACEOUS OOZE. 161 



or diatomite, and used as a polishing material, occur in many 

 parts of Britain, marking the sites of dried-up pools or lakes. 

 At the northern end of the island of Skye there occurs an 

 unusually pure deposit of diatomite overlain by peat and turf, 

 and extending over an area of fifty-eight square miles. Many 

 of the individuals in this deposit were in all probability carried 

 into the lake by running water, while others lived in the lake 

 and after death their tests contributed to the siliceous deposits 

 The late Dr Ehrenberg published numerous papers on dia- 

 tomaceous deposits in different parts of the world, and in his 

 great work, Zur Mikrogeologie', he gave numerous and beauti- 

 fully executed illustrations of such siliceous accumulations. In 

 many of the samples he figures one sees fragments of plant 

 tissues, spores of conifers and ferns, associated with the 

 diatom tests. The occurrence of the pollen grains of coni- 

 ferous trees in lacustrine and marine deposits is not surprising 

 in view of their abundance in Lake Constance and other lakes. 

 It is stated that the pollen of conifers in the Norwegian fiords 

 plays an important part in the nourishment of the Rhizopod 

 Saccamina^. 



In the waters of the ocean diatoms are of frequent occurrence, 

 and very widely distributed. Sir Joseph Hooker records the 

 existence of masses of diatomaceous ooze over a wide area in 

 Antarctic regions*. Along the shores of the Victoria Barrier, a 

 perpendicular wall of ice, between one and two hundred feet 

 above sea-level, the soundings were found to be invariably 

 charged with diatom remains, and from the base of the ice-wall 

 there appeared to be in process of formation a bank of these 

 tests stretching north for a distance of 200 miles. The more 

 extended researches conducted during the cruise of the 

 Challenger have clearly proved the enormous accumulations 

 of diatoms now being formed on the ocean-bed ^ South of 

 latitude 45° S. there is now being built up a vast deposit 

 which may be eventually upraised as a fairly pure siliceous 

 rock. From extreme northern latitudes Nansen has recently 



1 Wilson (87). ^ Ehrenberg (54). 



3 Noll (95) p. 248. * Hooker, J. D. (44) vol. i. p. 503. 



6 Murray, J. and Benard (91) p. 208. 



