126 NAUTICAL CHART MANUAL 



Ravine A gulch; a small gorge or canyon, the sides of which have 



comparatively uniform slopes. 

 Reach An extended portion of water or land; a straight portion of a 



stream or river; a level stretch, as between locks in a canal; 



an arm of the sea extending into the land; a promontory, 



tongue. 

 Reef (0-10) An off-shore consolidated rock hazard to navigation with a 



least depth of 10 fathoms or less (see also coral reef). 

 Relief (C-1 to 2b) The elevations or the inequalities, collectively, of a land 



surface. 

 Ridge A long and narrow elevation with steep sides; a long, narrow 



elevation of the sea floor, with steep sides and more irregular 



topography than a rise. 

 Rincon Corner or cove; an angular recess orhoUowbend in a mountain, 



riverbank, cliff, or the like (Local in Southwest) (Sp. origin.) 

 Rise A long, broad elevation that rises gently and generally smoothly 



from the sea floor. 

 River (C-13) A natural stream of running water, larger than a creek or 



brook. 



Run A brook or small creek; a small, swift watercourse. 



Saddle A low point on a ridge or crestline; a ridge connecting two higher 



elevations; a low point on a ridge or between seamounts. 

 Sand dune Low hills or ridges of sand formed by action of the wind (See 



"dune"). 

 Scarp An escarpment, cliff, or steep slope of some extent along the 



margin of a plateau, mesa, terrace, or bench. 

 Sea A large body of salt water, second in rank to an ocean, more or 



less landlocked and generally part of, or connected with, an 



ocean or a larger sea. 

 Seachannel A long, narrow, U-shaped or V-shaped, shallow depression of 



the sea floor, usually occurring on a gently sloping plain or 



fan. 

 Seamount An elevation of the sea floor having a nearly equidimensional 



plan less than 60 nautical miles across the smnmit. 

 Seamount chain Three or more seamounts in a line and with bases separated by 



a relatively flat sea floor. 

 Seamount group Three or more seamounts not in a line and with bases separated 



by a relatively flat sea floor. 

 Seamount range Three or more seamoimts having connected bases and aligned 



along a ridge or rise. 

 Shelf edge A line along which there is a marked increase of slope at the 



outer margin of a continental shelf or an island shelf. (For 



charting purposes the 100-fathom depth contour is normally 



accepted as the shelf edge; the actual depth usually is less 



but may be more.) 

 Shoal An off-shore hazard to navigation with a least depth of 10 



fathoms or less composed of unconsolidated material. 

 Shore (A-l to A-11) The narrow zone of land fronting any body of water. 



