Mountains and Valleys Below the Oceans

Do you have the map of all the underwater landscape?! It's kind of hard to visualize what you are talking about. Thanks!!

Almost any of the plate techtonics articles or text books will give detailed explanations of this phenomena. The reason these mountains are no tthat high is because they mark the spreading zones where magma slowly flows to the surface. Plate collision zones are for the most part located on land on the edges of continents and the subduction zones are just offshore. The Himalayas is perhaps one of the most violent collision zones on this planet. Steep and tall mountains are only to be found at volcanoe locations like Hawaii and Iceland. A number of sea mounts evidently represent ancient volcanoes and may have their flat tops submerged several hundred or more feet below present sealevels. Every so often a submarine collides with one of the uncharted sea mountians. For greater details look for bathysmetric charts of the oceans. These will give you incredible detail. Also check back into the National Geographic archives. At one time they published some beautiful charts of undersea details.

while on the subject of levels of these submerged ridges/mountains, what was the position 10000 years ago , when I gather the sea level was 9m below the present level.

It may show up that many places where you need boat to cross, one could have crossed by foot at that time.So Human migration was easy .

The Palk Strait which Hindus believes to be built by Lord Ram's soldeirs by depositing stones/earth for Lord Rama to cross with Army and recover his wife Sita from King Ravana , the King of Lanka.

But may be if we go back 10000 years and at 9m lower level , most of the distance was above the sea and small stretches were filled up for the passage.

Is there a Map of all these mountains when sea level was down by 9meters ?

You will not find a pretty map with the water printed in blue and land in brown or some other color, but its fairly easy to redraw the shoreline contour by using a depth contour of 9 meters. As for these "mountains"; a change in sea level of 9 meter (30 feet) would not make any real difference. If you look at the present day bathysmetric charts you wil see that the continental shelf extends out to the 100 fathom line. At that point there is a precipitous drop into what is termed the abbysal plain which is the real seafloor. roughly 10,000 - 13,000 feet deeper than the surface of the continental shelf edge.

Within the continental shelf area, the sea bottom slopes downward gradually to the edge. Waves and ocean currents have long ago washed away any loose soil and dirt. this process only takes a few years. Hard rocky outcrops will not erode so rapidly and today form islands. In the shallows of the English channel there are several places where monestaries and fortresses have been built on rocky outcrops. They are isolated at high tide but low tide expose sandy areas making it possible to walk or drive outo the buildings and the island. These sea mounts would still be in the same place and have pretty much the same contours as they did 10,000 years ago. The few exceptions being the volcanoes like Hawaii wher pillow lava that cools as soon as it touches the ocean hardens and forms an over hanging shelf. Scientists have measured some and calculated othe places where these shelfs extend a long way from the original shoreline.

A drop of 9 meters in sea level is not going to reveal many submerged mountains.

Hey, Del's turned into a fish, a "Catfish"?

Spencer

Google is also getting in on the act with Google Oceans. However don't rush for the flippers and wetsuit just yet - it might be a while before it is up and running (or swimming?)

Brgds, Maurice

Google must have been bought out by a hideous lawyer seeking to make some money parasitizing renewable energy developments.

http://www.learner.org/resources/series78.html

This site (and several other programs that are available at learner.org) - might keep you occupied on a rainy day.

No sense in me blabbering on about things you may already know, or to pretend to be an expert if you don't....when I can point you to to such terrific resources.