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Oh. XL] 



FLOATING ICE IN SEA OF THE WHITE CHALK. 



217 



1 ave been derived chiefly from plants called Diatoms. It was 

 ascertained, when soundings were made for the Electric Tele- 

 graph, that calcareous mud of a similar character and origin 

 •now forming over vast areas in the depths of the Atlantic. 



reneral absence from the white chalk of sand, pebbles, 

 drift-wood, and other signs of neighbouring land, is thus ac- 

 counted for, but the occasional discovery of single and per- 

 fectly isolated stones, usually consisting of quartz and green 

 schist, in the south-east of England, has naturally excited 

 much surprise. In what manner could such stones have been 



The 



bottom 



without any admixture of other foreign matter ? 



me 



endeavoured 



ma 



Mr 



size are occasionally entangled in the roots of floating trees, 

 and transported to great distances 



mid 



One of 



them as big as a man's head, was conveyed in this way for 



600 miles to Keelir 

 Indian Ocean. Sea 



Kelp 



om 



water pebbles and earth around which its roots have grown. 

 But on reconsidering all the facts now observed, I agree 



Mr 



some 



we cannot account for without introducing the agency of 



Thus, for example, in 1857, there was found at Pur- 



lce. 



ley, near Croydon, in the body of the white chalk, a group of 

 stones, the largest of which consisted of syenite, a rock com- 

 posed of augite and felspar. This block had been broken up 



examined 

 ments 



diameter 



wards of twenty-four pounds. It was surrounded by granitic 

 sand and pebbles of greenstone, and its dimensions rendered 

 the hypothesis of transportation by drift-timber inadmissible. 

 There was. moreover, a total absence of carbonaceous matter, 



mi 



had sunk on the spot. Mr. Godwin- Austen, therefore, has 



must 



into coast-ice, and then floated out to sea, and the stones, he 



