THE MICROSCOPE IN GEOLOGICAL INVESTIGATION. 



305 



of the Carboniferous period, 485, and the Nummulitic limestone of the 

 Eocene, 489), we interpret the phenomenon by the fact that the dredg- 

 ings obtained from certain parts of the ocean-bottom consist almost en- 

 tirely of remains of existing Foraminifera, in which entire shells, the 

 animals of which may be yet alive, are mingled with the debris of others 

 that have been reduced by the action of the waves to a fragmentary state. 

 Such a deposit consisting chiefly of OrUtolites, 466, is at present in 

 the act of formation on cer- 

 tain parts of the shores of 

 Australia, as the Author was 

 informed by Mr. J. Beete 

 Jukes; thus affording the 

 exact parallel to the stratum 

 of Orbitolites (belonging, as 

 his own investigations have 

 led him to believe, to the 

 very same species), that 

 forms part of the ' calcaire 

 grossier ' of the Paris basin. 

 So in the fine white mud 

 which is brought up from 

 almost every part of the 

 sea-bottom of the Levant, 

 where it forms the stratum 

 that is continually undergo- 

 ing a slow but steady in- 

 crease in thickness, the Mi- 

 croscopic researches of Prof. 

 Williamson 1 have shown, not 

 only that it contains multi- 

 tudes of minute remains of 

 living organisms, both Ani- 

 mal and Vegetable, but that 

 it is entirely or almost wholly 

 composed of such remains. 

 Amongst these were about 

 26 species of Diatomaceae 

 (siliceous), 8 species of Fora- 

 minifera (calcareous), and a 

 miscellaneous group of ob- 

 jects (Fig. 488), consisting 

 of calcareous and siliceous _ m 



spicule (unknown) ;'E, calcareous spicule of Grantid; F, o, 

 M, o portions of calcareous skeleton of Echinodermata; H, 

 i, calcareous spicule of Gorgonia; K, L, N, siliceous spicules 

 p, portion of prismatic layer of shell of 



gOni33, 



ragmentS 



calcareous skeletons of Echi- 



noderms and Mollusks. A 



collection of forms strongly resembling that of the Levant mud, with 



the exception of the siliceous Diatomaceae, is found in many parts of 



the ( calcaire grossier ' of the Paris basin, as well as in other extensive 



deposits of the same early Tertiary period. 



699. It is, however, in regard to the great Chalk Formation, that 

 the information afforded by the Microscope has been most valuable 



Memoirs of the Manchester Literary and Philosophical Society," Vol. vii. 

 20 



