Putting the Western Indian Ocean on the Map

By Spalding, Mark | Geographical, July 2004 | Go to article overview

Putting the Western Indian Ocean on the Map


Spalding, Mark, Geographical


Despite having been sailed by merchants for millennia, the western Indian Ocean wasn't properly explored until a century ago and it's only in the past decade that scientists have come to grips with this unique and fragile environment. Mark Spalding of the UNEP World Conservation Monitoring Centre explains the importance of this vast shallow sea to the east of Madagascar

Suppose you had to navigate with a map that read, "This mountain may lie three kilometres farther east than it is drawn." The world's best nautical charts of the more remote parts of many oceans are still littered with equivalent statements. The sea monsters are gone, but many marine charts still lack some vital information.

The western Indian Ocean is one such mare incognitum. Although traders from Arabia and East Africa sailed the coastal waters for millennia, few ventured into the open ocean.

The first efforts to explore these waters took place almost 100 years ago. The Percy Sladen Trust Expedition, led by J Stanley Gardiner, on a British hydrographic vessel, HMS Sealark. Over a period of seven months it covered a vast area, producing maps and marine charts (many of which are still the best available) and describing the flora and fauna.

In the years that followed, there was little else, except some small-scale scientific work, until the 1990s, when the Royal Geographical Society (with IBG) proposed the Shoals of Capricorn Programme, a comprehensive multidisciplinary research project that aimed to provide information about the region's environment and a plan for its management. In January 2004, the Royal Society hosted a meeting at which some of the more than 200 scientists who took part in the six-year programme presented their findings.

The area of interest stands out quite clearly on marine charts. It is some 90,000 square kilometres of shallow waters, known as the Mascarene Ridge or Plateau, bound by Madagascar to the east and an arc of islands from the Seychelles in the north to Mauritius in the south. Ten thousand years ago, at the end of the ice ages and the dawn of human civilisations, it would have been dry land, partly enclosing the Mascarene Basin as a sea. Today, unconnected to any continental shores, with only a few tiny islands, it is unique among the world's oceans.

One of the first tasks in exploration is the development, or improvement, of maps. Bathymetric charts of the oceans have been created and refined since the ages of European discovery. Back then, the relative simplicity of the available navigational and depth-sounding tools meant that gathering even single data points in the deep ocean was very laborious. Nevertheless, over the centuries, a broad picture of the sea floor gradually developed.

Modern technology has revolutionised this process. Satellite positioning, along with broad-beam and side-scan sonar, produces detailed, textured maps of the sea floor. Satellite altimetry has enabled researchers to map comprehensively the sea floor by measuring differences in the height of the sea's surface. The gravitational pull exerted by variations in the topography of the sea floor affects the height of the water, causing it to be higher, perhaps by just a few tens of centimetres, over an undersea mountain than over a deep trench. When the influence of waves and tides is averaged out, scientists can use these differences to calculate the sea floor's topography.

But there is still a long way to go. Satellite altimetry is low resolution and can't be used to develop fine-scale navigational charts, because it only picks up features of ten kilometres width or more. Developing more accurate charts using sonar systems still requires boats, time and resources. Information has poured in from the shipping lanes, but elsewhere the maps are bare.

The Mascarene Ridge is one such area. But the Shoals programme has precipitated great advances. In 1999 two naval survey vessels, HMS Scott and HMS Beagle, gathered detailed information on the deeper slopes to either side of the ridge. …

The rest of this article is only available to active members of Questia

Sign up now for a free, 1-day trial and receive full access to:

  • Questia's entire collection
  • Automatic bibliography creation
  • More helpful research tools like notes, citations, and highlights
  • Ad-free environment

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this article

This article has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this article

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited article

Putting the Western Indian Ocean on the Map
Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Full screen

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.