AMELIORATIONS OF PRESENT ARCTIC CLIMATES 397 



a) The Greater Gulf Stream. — The best-known portion of the 

 warm, poleward-moving surface currents has long been called, with 

 some looseness, the "Gulf Stream." For the general purposes of 

 this discussion, it will be convenient to acknowledge this looseness 

 frankly by using the broad term, the " Greater Gulf Stream," which 

 implies there is a narrower sense. Under this broad term let us 

 include all warm surface currents which directly or indirectly unite 

 in carrying heat into the polar regions. This great group may be 

 said to start with the warm, equatorial currents that flow north- 

 westerly along the northern coast of South America, gathering as 

 they go the fresh waters of the Amazon, the Orinoco, and other rivers 

 of South America, as well as the direct precipitation of the rainy 

 region they traverse. They are both warm and diluted. For the 

 larger part they enter the Caribbean Sea and through it reach the 

 Gulf of Mexico. In passing through these bodies they receive fur- 

 ther dilution from the rivers of the bordering coasts, notably the 

 great rivers of the Mississippi Basin. As is well known, the con- 

 figuration of the coasts turns these equatorial waters about to the 

 northeast and they issue from the gulf as the Florida current or the 

 true Gulf Stream, 



A part of the equatorial current, however, turns to the north- 

 east outside the Antilles and flows more or less parallel to the true 

 Gulf Stream until the two become practically indistinguishable 

 from each other. 



While the Gulf Stream is moving northeasterly near the coast 

 of North America, it appears from the maps of salinity (see Fig. 2)^ 

 to become rather suddenly much more saline than it was in the Gulf 

 of Mexico, and this holds measurably true far to the northeast. 

 The map of salinity probably requires much revision in detail to 

 represent the specific facts, for the data for a map of sahnity are as 

 yet very imperfect. Murray's chart is here accepted in its essen- 

 tials, with the presumption that fuller data will modify it in impor- 

 tant particulars. On Figure 2 it will be seen that there is notable 

 westward extension of the area of high salinity that centers in the 

 heart of the great evaporating tract, or, in other words, the Sar- 



' Sir John Murray, The Ocean, Plate III (in colors) . This is reproduced in colors 

 as a frontispiece in J. T. Jenkins' very recent (1921) A Textbook of Oceanography. Fig- 

 ure 2 of this article is a photographic copy of this. 



