548 DEEP-SEA DEPOSITS. 



after iTinuinerable examinatious, of marine sediments in comparatively 

 shallow regions, bordering continents and islands, and whicli we shall 

 designate here under the name of marginal. 



MARGINAL SEDIMENTS OF THE SEA. 



The configuration of the bottom of the ocean had drawn the atten- 

 tion of the ancients, and their observations on this subject, as upon 

 many others, proves the sagacity of the Greek philosophers. In a 

 special work Posidonius adopts the oi)inion expressed more than a 

 century before by the great geometrician, astronomer, and geographer, 

 Eratosthenes, that the earth, save for accidents which are imperceptible 

 in such dimensions, is spherical.* 



After having studied the three voyages of Eudoxus of Cyzique, Posi- 

 donius concludes that the ocean surrounds the inhabitable land, and 

 that a ship leaving the west with Eurus at the stern would arrive in 

 India after traversing a distance estimated by him at 70,000 stadia.f 

 The same author states that the depth of the sea near Saidinia reaches 

 nearly 1,000 or<jy€s, or Greek fathoms. (About 1850'".) This is proba- 

 bly the oldest notice of a deep sea sounding, and it is to be regretted 

 that the process by which it was obtained is not known. 



After the immortal discoveries of Christopher Columbus, of Vasco 

 de Gama, and Magellan, had added a hemisphere to the map of the 

 world, the knowledge of the .sphericity of the earth, of the existence 

 of the antipodes, gave rise to many new ideas. Magellan tried in his 

 voyage across the Pacific to measure its depth, but in vain. Up to 

 that time, that is to say, until the middle of the sixteenth century, a 

 depth greater than 400 meters had not been sounded. 



It is but just to recall here the name of Buache,| member of the 

 Academy of Sciences, who made in 1737 a first attempt to represent 

 the bed of the sea by the aid of contours. In a memoir published 

 in 1752 he says: "The use I have made of soundings, which no one 

 before myself had ever employed to represent the bottom of the sea, 

 seems to me very proper to show in an obvious manner the sloi)es or 

 declivities of the coasts, and carries us by degrees to the bed of the 

 basins of the sea." 



The nature of the material constituting the bed of the sea, Herod- 

 otus tells us had also been the subject of his meditations. 



Strabo, with the penetration and certainty of his judgment, § remarks 

 that the sea continues to receive without interruption the alluvium of 



*Strabo: Geography. Translation of Mr. Tardieu; vol. i, p. 85. 



t Same work, vol. i, p. 92. 



i Essay of Physical Geography, in Avhich general views are stated upon the 

 frame-work of the globe, composed of chains of mountains which traverse both 

 seas and lands, with some special considerations on the various basins of the sea 

 and upon its interior configuration. (History of the Academy of Sciences, 1752, 

 p. 399.) 



$ Strabo's Geography, translation above quoted, p. 92. 



