234 PRINCIPLES OF STRATKiRAPHY 



but rises to lOO or 120 nautical miles in the colder and warmer 

 seasons, i. c, 1.5 to 2.5 meters per second, a velocity which com- 

 pares favorably with that of many great rivers in their lower 

 reaches during high water. 



The western border of the Gulf Stream follows pretty closely 

 the edge of the continental shelf and remains more or less sharply 

 defined. It is often abruptly outlined by the rising of a wall of 

 cold water, the temperature of which in different seasons is from 

 10° to 20° lower than that of the Florida stream. This so-called 

 "cold wall" is an effective barrier to migration, and its displace- 

 ment by strong winds brings about anomalous bionomic results. 

 Eastward the current widens from 30 nautical miles in the straits 

 to twice that at Cape Canaveral, and becoming from 120 to 150 

 nautical miles wide opposite Charleston. It constantly increases 

 northward. Southeast of New York the average velocity has be- 

 come reduced to from 30 to 48 nautical miles per day, though some- 

 times it rises to ^2 nautical miles. The stream as such cannot 

 be traced beyond the meridian of the eastern border of the Great 

 Newfoundland banks, before reaching whicii it already begins to 

 break up into a series of separate streams of varying temperature. 

 The velocity of the West-wind drift becomes reduced to an average 

 of 12 or 15 nautical miles in mid-ocean, though as much as 48 

 nautical miles per day has been observed. The well-known mild 

 temperatures of the Uritish Isles, especially Ireland, where flowers 

 bloom in January, though the latitude is that of Labrador, are due 

 to the impingement against the coast of a branch of this warm 

 West-wind drift. Dividing on the British coast, both arms of this 

 branch enter the North Sea, one by way of the English Channel 

 and Dover Straits, and the other around the north coast, the Hebri- 

 des and Orkneys, while sending a third arm along the Norwegian 

 coast. A large part of the West-wind drift or "Irish Stream," 

 however, turns northward to Iceland, passing to the west of the 

 Faroe Islands and turning westward and southwestward as the 

 Irminger current, running parallel to the cold East Greenland 

 current and sending a branch around Cape Farewell into Davis 

 Straits. Throughout this course the velocity of the current is prob- 

 ably less than 21 cm. per second. From the west coast of Davis 

 Straits the cold southward-flowing Labrador current runs past the 

 Newfoundland coast and the eastern border of the Grand Banks 

 and disappears on reaching the Gulf Stream. This disappearance 

 has been regarded as due to a "swallowing" of the cold water by 

 the warm, or to a submergence of the cold beneath the warm, but 

 is probably due rather to dispersal as suggested by Kriimmel. Part 



