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SEA AND LAND 





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and dark waters of these regions, and, in part, in the tropical 

 climate of its surface. 



We have already alluded to the coldness of the water 

 wliich is found at great depths beneath the surface of even the 

 warmest parts of the open oceans. Wherever in such situa- 

 tions examinations of the temperature at the bottom have 



been made, it has been found to 

 be very near the freezing point. 

 There seems to be but one 

 possible explanation of this sin- 

 gular fact, which is the follow- 

 inof, viz. : On the surface of the 

 oceans there is a system of 

 warm currents, such as the 

 Gulf Stream, which flow in 

 great volume from the tropics 

 toward the poles. These tides 

 of water have to be, in some 

 manner, returned to the trop- 

 ical districts. In part this is 

 effected by certain counter cur- 



A member of the Foraminifcra, a group of 

 lowly animals which live in the superficial parts reUtS wllich Set SOUthward alottg 

 of the warm open sea, and whose remains fall in 



great quantities to the bottom. (Much manni- the SUrfaCe of the Sea \ but 

 fied.) 



the volume of these superficial 

 movements flowing toward the tropics is small as compared 

 with the streams which flow over the surface into the circum- 

 polar seas. The principal return or compensating movement 

 of the water appears to be brought about by a massive drift 

 of the fluid which has been chilled nearly to the freezing point 

 in high latitudes and then creeps, probably with extreme slow- 

 ness, along the bottom until it may attain the equator. There, 



Globergerina 



