GROUNDED HUMMOCK 



grounded hummock — A hummock which has 

 stranded on the bottom, either during its forma- 

 tion or later upon drifting into shallow water. 

 Grounded hummocks appear either singly or in 

 lines (or chains). 



grounded ice — See shore ice. 



ground ice — 1. See anchor ice for preferred 

 definition. 



2. Glacial or sea ice that has been covered 

 with soil. 



ground motion — The displacement of the ground 

 caused by the passage of elastic waves, arising 

 from earthquakes, explosions, seismic shots, 

 machinery, wind, traffic, and other causes. (35) 



ground swell — A long high ocean swell ; also, this 

 swell as it rises to prominent height in shallow 

 water, although usually not as high or dangerous 

 as blind rollers. (61) 



ground wave — The sound (seismic) wave whose 

 path is partially through water and partially 

 within the sediments, or rocks, beneath the ocean 

 bottom. (35) 



group velocity — The velocity of a wave disturb- 

 ance as a whole, that is, of an entire group of 

 component simple harmonic waves. 



For water surface waves, the group velocity 

 of deepwater waves is equal to one-half the 

 velocity of individual waves in the group; for 

 shallow water waves, it is the same as their 

 velocity. (5) 



growler — A piece of ice smaller than a bergy bit, 

 which often appears greenish in color and barely 

 shows above water. It may originate from sea 

 ice and glacier ice. (74) 



growler ice — An ice pack of growlers. (59) 

 Rare. 



Guiana Current — A current flowing northwest- 

 ward along the northeast coast of South America 

 (theGuianas). 



The Guiana Current is an extension of the 

 South Equatorial Current. Eventually, it 



joins the North Equatorial Current and sets 

 through the Lesser Antilles to become the Carib- 

 bean Current. 



Guinea Current — A current flowing eastward 

 along the south coast of northwest Africa into 

 the Gulf of Guinea. 



The Guinea Current originates from the 

 Equatorial Countercurrent which flows east 

 across the equatorial Atlantic. 



gulder — A double low water occurring on the 

 south coast of England. xS'ee double tide. (68) 



gulf — A large embayment in the coast in which 

 the entrance generally is wider than the length. 



gulf ice — Winter ice formed in a gulf or bay. 

 (59) Eare. 



Gulf Stream — A warm, well-defined, swift, and 

 relatively narrow ocean current which originates 

 north of Grand Bahama Island where the Flor- 

 ida Current and the Antilles Current meet. 

 The Gulf Stream extends to the Grand Banks at 

 about 40°N, 50°W where it meets the cold 

 Labrador Current, and the two flow eastward 

 as the North Atlantic Current. 



The Florida Current, Gulf Stream, and North 

 Atlantic Current together form the Gulf Stream 

 system. Sometimes the entire system is referred 

 to as the Gulf Stream. See wind-driven 

 current. 



Gulf Stream system — The Florida Current, 

 Gulf Stream, and North Atlantic Current, 

 collectively. 



gulf weed — See Sargassum. 



gully — This tenn is not recommended by the 

 ACUF for a relatively narrow ravine in the 

 ocean bed. See seachannel, trench. 



gut — A narrow channel or strait. ( 68 ) 



guyot — This term is not recommended by the 

 ACUF for a seamount. See tablemount. 



gyre — A closed circulatory system, but larger than 

 a whirlpool or eddy. 



74 



