296 



THE NATURE BOOK 



ture. Then there was also the question 

 of the preponderance of the oval-cham- 

 bered bodies in the chalk, and the in\ari- 

 able absence of those organic remains 



A SECTION OF CHALK, SHO^XrING FOSSIL RE- 

 MAINS OF FORAMEMFER/E AND SPONGE 

 SPICULES. 



which are always prevalent in ordinary 

 limestone ; and why flint, which is so 

 rare in ordinary limestone, should be so 

 abundant in the chalk. The fossil remains 

 of sea-urchins, marine shells, corals, fishes, 

 etc., all proved that the chalky like the 



A THIN SECTION OF CHALK IS SEEN TO BE 

 CHIEFLY COMPOSED OF THE SHELLS OF 

 GLOBIGEKINA. 



majority of the limestones, must have 

 been formed beneath the surface of the 

 sea, without, however, accounting fur 



the characteristic differences of the two 

 formations. 



It has been one of the triumphs of 

 biology that it has solved these puzzling 

 questions, and clearly demonstrated how 

 the chalk has been formed ; and it is to 

 the able and untiring investigations of 

 the late Professor Huxley, Dr. Wallich, 

 and Dr. Ehrenberg that the problems of 

 the chalk formation have been solved. 



Prior to the laying down of the first 

 telegra])h cable between Ireland and New- 

 foundland, a survey was made of that 

 part of the bed of the sea upon which the 

 cable was to rest ; and the samples of 

 mud dredged up during this survey were 

 sent for microscopic examination to Pro- 

 fessor Huxley and Dr. Ehrenberg. The 

 mud obtained by the survey expedition 

 was generally a whitish-grey in colour, and 



IN THE CHALK CLIFFS AT DOVER. 



because of its peculiar characteristic 

 appearance received the name of " ooze." 

 \Vhcn some of this ooze was examined 

 under the microscope, it was at once seen 

 to be largely composed of the same globular 

 bodies tliat are such an important charac- 

 teristic of the chalk — ^the shells of a most 

 interesting minute creature called, from 

 its globular shape, the Globigerina. So, 

 on account of the predominance of these 

 globular shells in the mud, it has been 

 called the " (rlobigerina ooze." 



The result of these deep-sea dredg- 

 ings and their microscopical examination 

 was to demonstrate that o\'er a great 

 ])art of the bed of the North Atlantic 

 a very wonderful deposit ul tlie (ilobi-' 

 gerina ooze is being formed. This con- 

 sists almost entirely of an aggregation 

 of the microscopic shells of the Globi- 

 gerina, a creature belonging to a wonderful 



