Editing Atlantic Ocean (section)

=== Ocean floor ===
{{For|a list of fracture zones in the Atlantic|List of fracture zones#Atlantic Ocean}}
[[Continental shelf|Continental shelves]] in the Atlantic are wide off Newfoundland, southernmost South America, and northeastern Europe.
In the western Atlantic [[carbonate platform]]s dominate large areas, for example, the [[Blake Plateau]] and [[Bermuda Rise]].
The Atlantic is surrounded by [[passive margin]]s except at a few locations where [[active margin]]s form deep [[oceanic trench|trenches]]: the [[Puerto Rico Trench]] ({{cvt|8376|m|disp=or}} maximum depth) in the western Atlantic and [[South Sandwich Trench]] ({{cvt|8264|m|disp=or}}) in the South Atlantic. There are numerous submarine canyons off northeastern North America, western Europe, and northwestern Africa. Some of these canyons extend along the continental rises and farther into the abyssal plains as deep-sea channels.<ref name="LevGood-2003" />

In 1922, a historic moment in cartography and oceanography occurred. The USS ''Stewart'' used a Navy Sonic Depth Finder to draw a continuous map across the bed of the Atlantic. This involved little guesswork because the idea of sonar is straightforward with pulses being sent from the vessel, which bounce off the ocean floor, then return to the vessel.<ref name="the Atlantic">{{Cite book|title=The Great Deep|last=Hamilton-Paterson|first=James|date=1992|author-link=James Hamilton-Paterson}}</ref> The deep ocean floor is thought to be fairly flat with occasional deeps, [[abyssal plain]]s, [[oceanic trench|trenches]], [[seamount]]s, [[Oceanic basin|basins]], [[Oceanic plateau|plateaus]], [[Submarine canyon|canyons]], and some [[guyot]]s. Various shelves along the margins of the continents constitute about 11% of the bottom topography with few deep channels cut across the continental rise.

The mean depth between [[60th parallel north|60°N]] and [[60th parallel south|60°S]] is {{cvt|3730|m}}, or close to the average for the global ocean, with a modal depth between {{cvt|4000|and|5000|m}}.<ref name="LevGood-2003" />

In the South Atlantic the [[Walvis Ridge]] and [[Rio Grande Rise]] form barriers to ocean currents.
The [[Laurentian Abyss]] is found off the eastern coast of Canada.