248 



HYDROGRAPHIC MANUAL 



specific name is seldom applied to this term, 

 it is used very often on charts. 



narrows. Usually the most restricted part 

 of a passage between islands or between an 

 island and the mainland. 



neck. A term used in several ways, as (a) 

 the equivalent of an isthmus, (b) a small 

 peninsula, (c) the land areas between 

 streams flowing into a sound or bay. 



pass or passage. A waterway between is- 

 lands, islands and the mainland, or between 

 large groups of islands. A pass is usually a 

 larger feature than a passage which is more 

 comparable to a narrows. 



point. The extreme end of a cape, or the 

 outer end of any land area protruding into 

 the water and smaller than a cape. The 

 two terms are not interchangeable. 



river. A stream of water larger than a 

 creek flowing into another river, a lake, or the 

 sea. In some areas the term river has been 

 applied to streams no larger than brooks; 

 conversely the term creek has been applied 

 to streams which are ordinarily classified 

 as rivers. 



slough. A minor marshland or tidal 

 waterway which usually connects other tidal 

 areas; often more or less equivalent to a 

 bayou ; occasionally applied to the sea level 

 portion of a creek on the West coast. 



sound. A long passage of water connect- 

 ing two larger bodies but too extensive to 

 be termed a strait or pass. The term has 

 been applied to many features which do not 

 fit the accepted definition. Many are very 

 large bodies of water, such as Mississippi 

 Sound and Prince William Sound, others are 

 mere salt water ponds or small passages be- 

 tween islands. 



spit. A small tongue of land, usually low 

 and narrow, extending into a body of water 

 and generally continuing in a long narrow 

 shoal for some distance from the shore. 



strait. A passageway connecting two 

 large bodies of water. The term is applied 

 indiscriminately to waterways of all sizes 

 both in length and width. 



The terms pass, passage, strait, and nar- 

 rows, are generally indicative of the same 

 type of feature. The term "channel" has 



been used frequently in the name of such 

 natural features, but is ordinarily limited 

 to an improved waterway. As a general rule 

 the terms passage and narrows are applied 

 in speaking of features smaller than a pass 

 or strait. 



stream. Occasionally used in place of 

 creek or brook especially in Maine and Hawaii. 



thorofare. This shortened form of 

 thoroughfare has become standard for a 

 natural waterway in marshy areas. It is the 

 same type of feature as a slough or bayou. 



B. Submerged Features 



bank. An elevation of the sea floor located 

 on a continental shelf or an island shelf 

 and over which the depth of water is rela- 

 tively shallow but sufficient for safe surface 

 navigation. 



basin. A depression of the sea floor more 

 or less equidimensional in form. When the 

 length is much greater than the width, the 

 feature is a trough. 



canyon. A relatively narrow, deep valley 

 with steep slopes, the bottom of which grades 

 continually downward. 



continental shelf. A zone adjacent to a 

 continent and extending from the low water- 

 line to the depth at which there is a marked 

 increase of slope to greater depth. 



continental slope. A declivity from the 

 outer edge of a continental shelf or con- 

 tinental borderland into greater depths. 



Cordillera. An entire mountain province, 

 including all the subordinate mountain ran- 

 ges and groups and the interior plateaus and 

 basins. 



deep. A relatively small area of excep- 

 tional depth found in a depression. The term 

 is generally restricted to depths greater than 

 3000 fathoms. 



dome. A small elevation on a continen- 

 tal or island shelf with a characteristically 

 rounded profile. 



escarpment. An elongated and compar- 

 atively steep slope of the sea floor, separat- 

 ing flat or gently sloping areas. 



fan. A gently sloping, cone-shaped accu- 

 mulation of material normally located at 

 the mouth of a submarine canyon. 



