Our navigation bar is loading . . . . . .


Advertise on JCSM - Hear JCSM's Weekly Devotions via Podcast/RSS Feed! - Skip These Ads

You can advertise your site right here!Click here to learn more!

 10,000 Wise Quotes and Spiritual Sayings by Jason Gastrich, Ph.D.

 JCSM's Top 1000 Christian Sites - Free Traffic Sharing Service! Join the Online Christ-Centered Ministries!

-
Jesus Christ Saves Ministries

Click here and add this page to your favorites!

Return to the JCSM Study Center!

Encyclopedia Britannica



HORIZONTAL

This article appears in Volume V23, Page 381 of the Encyclopedia Britannica.

Encyclopedia Britannica - Main :: HIG-HOR
HORIZONTAL SCALE
delta
  in front of an outlet is proportionate to the size of the channel, and the length of the jetties required for lowering the bar by scour in front of any channel is proportionate to the discharge of the channel. Consequently, the conditions are more unfavourable for the improvement of the outlets of the larger
delta
  channels than of the smaller ones; though, on the other hand, the larger channels crossing the delta are generally more suitable for navigation on account of their size, and the natural depth over their bars is greater owing to the larger discharge.
The discharge of the main branch of the Rhone, which formerly flowed into the Mediterranean and the Gulf of Foz through six Rhone. mouths, was in 185257 concentrated in the direct eastern
channel by embankments along sides, which closed all the lateral channels. The entire flow of the river, being thus discharged through the eastern outlets, increased for a time the depth over its bar from 41 ft. to 91 ft.; but as the
great
  volume of
alluvium
  brought down, including an unusually large proportion of sand rolled along the bed of the river, was also all discharged through the. one outlet, the bar soon formed again farther out, and naturally advanced with the delta in front of the outlet more rapidly than formerly when the deposit was distributed through six divergent mouths. Accordingly, the very moderate deepening produced by the embankments was not iong maintained, and the
average
  depth over the bar has not exceeded 61 ft. for many years past; the St Louis Canal was constructed to provide a deeper outlet for the navigation.' This want oI success was due to the selection of an outlet opening on a sheltered, somewhat shallow bay, instead of a southern outlet discharging into deep water in the Mediterranean and having a deep littoral current flowing across it, and also resulted from the closing of all the-other outlets, whereby the whole of the deposit, as well as all the discharge, was concentrated in front of the badly situated eastern outlet. The southern Roustan branch was reopened in 1893 to prevent the silting-up of the outlet of the St Louis Canal.
The Danube traverses its delta in three branches, the northern one of which, though conveying nearly two-thirds of the discharge Danube. of the river, is unsuitable for improvement owing to its
splitting up along portions of its course into several channels, and eventually flowing into the sea through twelve mouths of a small independent delta advancing about 250 ft. annually across a shallow
foreshore
 . The central Sulina branch was selected for improvement in 1858 in preference to the southern St George's branch, which had a more favourably situated outlet and a better channel through the delta, on account of the much smaller expenditure required for carrying out jetties to the bar in front of the Sulina outlet, which was only half the distance from the shore of the bar of the St George's outlet, owing to the much smaller discharge of the Sulina branch.2 The jetties, begun provisionally in 1858 and subsequently consolidated and somewhat extended, were finally completed in 1877. They increased the depth over the bar from an
average
  of about 9 ft. previously to 1858 up to 201 ft. in 1873, which was maintained for many years. In 1893, however, the increasing
draught
  of vessels rendered a greater depth necessary; the wide Inshore portion of the jetty channel was therefore narrowed by inner parallel jetties, and a powerful dredger was set to
work
  in the jetty channel and outside, whereby the depth was increased to 24 ft. in 1897, and was fairly maintained up to 1907, when a second dredger became necessary to
cope
  with the shoaling. The somewhat small ratio of sediment to discharge in the Danube, the fineness of the greater portion of this sediment, its comparatively moderate amount owing to the small proportion of the discharge flowing through the Sulina branch, and its partial dispersion by the southerly littoral current and wave action, have prevented the rapid formation of a shoal in front of the Sulina outlet. Nevertheless, the lines of soundings are gradually advancing seawards in the line of the outlet channel, and there are signs of the formation of a new bar farther out, whilst the deposit to the
south
  by the current and waves has deflected the deepest channel northwards. Accordingly, a prolongation of the jetties will eventually be necessary, notwithstanding the removal of a portion of the deposit from the outlet channel by dredging.
The selection of the outlet of the
south
  pass of the Mississippi delta for improvement by parallel jetties in 1876-79, in spite of the
Mlsals- south-west pass possessing a larger channel and a better
slppl depth over its bar, was due, as at the Danube, to motives
of
economy
 , as the bar of the south-west pass was twice as far off from the shore as that of the south pass (fig. 13). There fascine mattress jetties, weighted with limestone, and with large concrete blocks at their exposed ends (see JETTY), 21 and 12 m. long, and curved slightly southwards at their outer ends to direct the sediment-bearing current more directly at right angles to the westerly littoral current, increased the depth of 8 ft. over the bar in 1875 up to 31 ft. between the jetties and out to deep water (fig. 14). The prolonged current of the river produced by the jetties has, as at the Sulina outlet, carried the main portion of the heavier sediment into fairly deep water, so that the greatest advance of theforeshore in front of the south pass has occurred in the 7o-ft. line of soundings, though the shallower soundings have also advanced.


End of Article: HORIZONTAL


If you wish, you can link directly to this article.
<a href="http://jcsm.org/StudyCenter/Encyclopedia/HIG_HOR/HORIZONTAL.html">
HORIZONTAL
</a>
(Previous)
HORIZON (Gr. 6pfTwv, dividing) 		(Next)
HORIZONTAL PRESSURES ON VERTICAL JOINTS

 


 

Jesus Christ Saves Ministries

The JCSM Study CenterAmerica's Christian FoundationSkeptic's Annotated Bible: Corrected and ExplainedNKJV Web Hosting and Services
JCSM's Sermons, Debates and the Bible on MP3The Online Christ-Centered MinistriesDo You Have A Web Site?  Your Ad Could Be Here!Seminary Notes and PapersThe Picturesque Photo Albums


Jesus Christ Saves Ministries, P.O. Box 70696, Pasadena, CA 91117

JCSM is a 501(c)(3), non-profit organization. Copyright © 1997-present.


Kingdom Debt Solutions - Be Debt Free! Sport Logos - Quality Athletic Equipment The JCSM Study Center Your Ad Could Be Here! Launch A Successful Internet Organization or Business! Learn Guitar, Bass, or Piano in San Diego county!

You can advertise your site right here!

Free & Cheap Cell Phones  |  Cheap Long Distance Phone Service Carriers  |  Talk America Local Phone Service  |  Ztel & MCI - Unlimited Long Distance
Compare Cell Phone Plans & Companies  |  International Calling Cards & Prepaid Phone Cards  |  Voice Over IP Broadband Internet Phone Service  |  Wireless Phone Plans & Cheap Cell Phones

Dr. Jason Gastrich

Jason Gastrich, Ph.D.

 

Jesus Christ Saves Ministries is directed by Dr. Jason Gastrich.  It was founded in 1997 and it exists to bring people into a life-changing and productive relationship with Jesus Christ.  JCSM offers over 200,000 free web pages, discussion boards, weekly html and mp3 devotionals, free email accounts, and much more.

Jesus Christ Saves Ministries
P.O. Box 9297
San Diego, CA  92169
1-877-850-3878 or Email

JCSM is a 501(c)(3), non-profit organization. Copyright © 1997-2008.

_____________________________________________________________________________

Online First Aid and CPR Certification  .  The Online Christ Centered Ministries  .  The Skeptic's Annotated Bible: Corrected and Explained  .  The Inerrancy Discussion Board  .  Free Email Accounts  .  Home Equity Loans  .  JasonGastrich.com  .  The Missions, Apologetics, and Creation Bible Conference  .  Young Earth Creation Science  .  San Diego Music Lessons  .  10,000 Wise Quotes and Spiritual Sayings  .  Gastrich.net  .  Maximizing the Internet: 12 Keys to Success  .  Louisiana Baptist University  .  NKJV Web Hosting and Services  .  Michael Newdow  .  San Diego Soccer Training  . Christian Guitar Lessons  .  Jesus Christ Saves Ministries  .  Eternal Security