Editing Tributary (section)

==Terminology==
[[File:Harpers Ferry WV aerial.jpg|thumb|upright=1.1|At [[Harpers Ferry, West Virginia]], looking downstream, the [[Shenandoah River]] (bottom right) meets the [[Potomac River]], which flows from bottom left to top right, making the Shenandoah a '''right tributary''' of the Potomac.]]
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''Right tributary'', or ''right-bank tributary'', and ''left tributary'', or ''left-bank tributary'', describe the orientation of the tributary relative to the flow of the main stem river. These terms are defined from the perspective of looking downstream, that is, facing the direction the [[Current (stream)|water current]] of the main stem is going. In a [[Inland navigation|navigational]] context, if one were floating on a [[raft]] or other vessel in the main stream, this would be the side the tributary enters from as one floats past; alternately, if one were floating down the tributary, the main stream meets it on the ''opposite'' bank of the tributary. This information may be used to avoid [[Whitewater|turbulent]] water by moving towards the opposite bank before approaching the confluence.<ref name=FS>{{cite web|author-last1=Bisson|author-first1=Peter|author-last2=Wondzell|author-first2=Steven|url=http://file.dnr.wa.gov/publications/lm_hcp_oesf_dec09_riparian_synthesis.pdf|title=Olympic Experimental State Forest Synthesis of Riparian Research and Monitoring|publisher=[[United States Forest Service]]|page=15|date=1 December 2009}}</ref>

An ''early tributary'' is a tributary that joins the main stem river closer to its source than its mouth, that is, '''before''' the river's [[midpoint]]; a ''late tributary'' joins the main stem further downstream, closer to its mouth than to its source, that is, '''after''' the midpoint.

In the United States, where tributaries sometimes have the same name as the river into which they feed, they are called '''forks'''. These are typically designated by compass direction. For example, the [[American River]] in California receives flow from its North, Middle, and South forks. The [[Chicago River]]'s North Branch has the East, West, and Middle Fork; the South Branch has its South Fork, and used to have a West Fork as well (now filled in).

Forks are sometimes designated as right or left. Here, the handedness is from the point of view of an observer facing upstream. For instance, [[Steer Creek (West Virginia)|Steer Creek]] has a left tributary which is called Right Fork Steer Creek.

These naming conventions are reflective of the circumstances of a particular river's identification and charting: people living along the banks of a river, with a name known to them, may then float down the river in exploration, and each tributary joining it as they pass by appears as a new river, to be given its own name, perhaps one already known to the people who live upon its banks. Conversely, explorers approaching a new land from the sea encounter its rivers at their mouths, where they name them on their charts, then, following a river upstream, encounter each tributary as a forking of the stream to the right and to the left, which then appear on their charts as such; or the streams are seen to diverge by the [[cardinal direction]] (north, south, east, or west) in which they proceed upstream, sometimes a third stream entering between two others is designated the ''middle'' fork; or the streams are distinguished by the relative height of one to the other, as one stream descending over a [[Waterfall|cataract]] into another becomes the ''upper'' fork, and the one it descends into, the ''lower''; or by relative volume: the smaller stream designated the ''little'' fork, the larger either retaining its name unmodified, or receives the designation ''big''.<ref name="Stewart 1939 p. 191">{{cite journal|last=Stewart|first=George R.|title=Nomenclature of Stream-Forks on the West Slope of the Sierra Nevada|journal=American Speech|volume=14|issue=3|date=1939|pages=191–197 |doi=10.2307/451418|jstor=451418 }}</ref>