# Ocean has shelves? **URL:** \ **Category:** Factual Questions\ **Created:** [March 13, 2003, 7:59am UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060 "2003-03-13T07:59:10Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Fuel](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@Fuel](https://boards.straightdope.com/u/Fuel)\ **Post date:** [March 13, 2003, 7:59am UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060/1 "2003-03-13T07:59:10Z")
I vaguely remember learning somewhere that the ocean has shelves and has physically elevated sections going farther out to sea from the shore. Does anyone know what I am talking about here? How does this work ect.? Does the ocean “bulge” in the middle? P.S. I am talking about the surface of the water being elevated or having different elevations other than the natural curvature of the earth. Sort of like water mountains/hills maybe? ---
**Author:** ![ChalkPit](https://avatars.discourse-cdn.com/v4/letter/c/a88e4f/32.png) [@ChalkPit](https://boards.straightdope.com/u/ChalkPit)\ **Post date:** [March 13, 2003, 8:03am UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060/2 "2003-03-13T08:03:49Z")
At first, I thought I knew what you were talking about. Then I read your P.S. and now I’m not so sure. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [March 13, 2003, 8:13am UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060/3 "2003-03-13T08:13:06Z")
What ChalkPit said. The surface of the ocean is, by definition, at sea level. Well, barring waves and whatnot. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [March 13, 2003, 8:22am UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060/4 "2003-03-13T08:22:53Z")
> [@](#): > > At the Panama Canal, the difference between the average sea level of the Atlantic Ocean and Pacific Ocean is about eight inches higher on the Pacific side. Interestingly, they mention our beloved Cecil [here.](http://geography.about.com/library/faq/blqzpanamaocean.htm) ---
**Author:** ![Omniscient](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omniscient/32/3290_2.png) [@Omniscient](https://boards.straightdope.com/u/Omniscient)\ **Post date:** [March 13, 2003, 8:35am UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060/5 "2003-03-13T08:35:26Z")
The ocean bulges due to tides. But does the contour of the ocean floor directly effect the waterline above it? I kinda doubt it, but I can’t offer any details to confirm so. ---
**Author:** ![donkeyoatey](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@donkeyoatey](https://boards.straightdope.com/u/donkeyoatey)\ **Post date:** [March 13, 2003, 9:25am UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060/6 "2003-03-13T09:25:07Z")
It does a little because of the ocean floor and also currents. From [this page](http://esapub.esrin.esa.it/eoq/eoq56/eoq56pp36-39.pdf). > [@](#): > > The ocean surface contains hills and valleys which are an image of the relief of the ocean bed. In addition, the oceans are in dynamic systems. For example warm and cold currents collide and the rotation of the Earth sets up circulation patterns producing elevations of the sea surface… > > The correllation of the gravity field with sea-surface anomalies showed that a change of 1 mgal produced a 1.7 m variation in sea level ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [March 13, 2003, 11:40am UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060/7 "2003-03-13T11:40:09Z")
Wind and wave transports water and thus produces “hills” in the surface of the sea. [This site](http://chswww.bur.dfo.ca/danp/fluctuations_e.html) describes the effects in the great lakes, but the same processes also occur in the oceans: > [@](#): > > (water level) fluctuations, lasting from a less than an hour to several days, are caused by meteorological conditions. The effect of wind and differences in barometric pressure over the lake surface create temporary imbalances in the water level at various locations. Storm surges are largest at the ends of an elongated basin, particularly when the long axis of the basin is aligned with the wind. In deep lakes such as Lake Ontario, the surge of water level rarely exceeds 0.5 metre, but in shallow Lake Erie, water-level differences from one end of the lake to the other of more than 5 metres have been observed. ---
**Author:** ![John\_Kentzel-Griffin](https://avatars.discourse-cdn.com/v4/letter/j/ccd318/32.png) [@John\_Kentzel-Griffin](https://boards.straightdope.com/u/John_Kentzel-Griffin)\ **Post date:** [March 13, 2003, 3:35pm UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060/8 "2003-03-13T15:35:41Z")
Are you thinking about continental shelves? That’s where the ocean is relatively shallow for some distance out from the continents. ---
**Author:** ![clayton\_e](https://avatars.discourse-cdn.com/v4/letter/c/c57346/32.png) [@clayton\_e](https://boards.straightdope.com/u/clayton_e)\ **Post date:** [March 13, 2003, 3:38pm UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060/9 "2003-03-13T15:38:54Z")
[Here](http://www-bprc.mps.ohio-state.edu/foram/maps/arctic1.gif) is a pretty good visual of what they look like. ---
**Author:** ![Fuel](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@Fuel](https://boards.straightdope.com/u/Fuel)\ **Post date:** [March 13, 2003, 6:18pm UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060/10 "2003-03-13T18:18:40Z")
Whoa, that’s a cool pic. Thanks for your replies. Our world is an amazing one. **Smeghead** , you catch the last couple posts?! By definition? Don’t be so closed-minded bud. 🙂 ---
**Author:** ![Zenster](https://avatars.discourse-cdn.com/v4/letter/z/cdc98d/32.png) [@Zenster](https://boards.straightdope.com/u/Zenster)\ **Post date:** [March 13, 2003, 8:10pm UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060/11 "2003-03-13T20:10:00Z")
Though mentioned much less often in scientific discussion, nearby the continental shelf can also be found the continental sofa and continental coffee table. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [March 14, 2003, 9:01am UTC](https://boards.straightdope.com/t/ocean-has-shelves/161060/12 "2003-03-14T09:01:10Z")
> [@](#): > > \*Originally posted by Fuel \* > \*\ ***Smeghead** , you catch the last couple posts?! By definition? Don’t be so closed-minded bud. 🙂 \*\* I was aware of those minor variations. Really! But even in those cases, the local sea level is still, by definition, sea level, even if it’s an inch or so higher than sea level elsewhere.