Equatorial or Meridial Ocean

Question

I am building a world that is mostly land but i need something to divide it all up a bit so i decided I'm adding an ocean.

What i want to know is the following: Would it be even remotely possible for a planet to either have an ocean across its equator (Big northern continent and Southern continent divided by an ocean), or have a ''meridian'' ocean (Big western continent and eastern continent divided by an ocean running along the planet's prime meridian)?

EDIT: To clarify. by ocean I mean not a sprawling one like earth has but more like a strip spanning either along the equator or along the meridian. (Like my examples above.)

Earth has a "big eastern continent" (Eurasia + Africa) and a "big western continent" (the Americas), separated by a "meridian ocean", so it is certainly possible. Just saying. (Why meridian and not meridial? Because it's a Latin word and that's how Latin works; it means "mid-day", as an adjective. The word "meridian" is short for "meridian circle", as "parallel" is short for "parallel circle".) — AlexP, Nov 14 '18 at 20:56
And remember that the Atlantic was once a narrow strip of water and it then it grew wider and wider; it is still widening. — AlexP, Nov 14 '18 at 21:06
Ah, pictures. You do understand that the vast majority of evaporation takes place in the ocean, and the planet in the pictures would consist mostly of bone-dry deserts? — AlexP, Nov 14 '18 at 21:12
I see, well a desert was not my intention. Hmmm…. would adding two additional oceans at the poles solve this desert problem? — Blue Devil, Nov 14 '18 at 21:14
Further to my answer below: you are guaranteed deserts I'm afraid. Polar oceans will help give a not-desert zone near them (assuming they aren't frozen -- which requires a planet somewhat warmer than earth), but such a zone will be small relative to the size of the planet. What do you need for your story? — Mark_Anderson, Nov 14 '18 at 21:19
Earth's ocean covers 3/4 of the planet's surface, and yet the interior of large continents such as Asia (and, partially North America) is mostly desertic... To reduce inlad dryness you need to accelerate the water cycle by making the planet quite a bit warmer than Earth is now, similar to what Earth had in the Carboniferous period. (On a geological scale, Earth is unusually cool. For most of Earth's history there were no ice caps at the poles.) — AlexP, Nov 14 '18 at 21:20
What i basically need is a planet with two continents (i would prefer to not have more) with a climate (and geography) somewhat like Iceland. With barren plains and desolate highlands but also a few (if needed coniferous) forests. — Blue Devil, Nov 14 '18 at 21:27
I think the question that needs asking here is: What's stopped oceans of ground water from pooling/emerging elsewhere simultaneous to this one? The Atlantic did begin as a narrow meridian of water, but much of the Earth's surface elsewhere was water too. — rek, Nov 17 '18 at 03:44
You might be interested in checking out these two questions: https://worldbuilding.stackexchange.com/questions/3598/how-would-tectonics-behave-on-a-two-continent-planet && https://worldbuilding.stackexchange.com/questions/19788/how-would-flora-behave-on-a-two-continent-planet — dot_Sp0T, Nov 17 '18 at 08:56

Mark_Anderson · Answer 1 · 2018-11-14T21:14:23.523

Yes. The configurations you describe are entirely possible and are believed to have direct analogues in the Earth's past. We currently have an East-West divide in our major continental bodies (Americas vs. Afro-Eurasia), and the North-South split is pretty much what the Tethys ocean did to godwanaland about 200 million years ago if I recall correctly.

If you wish to get technical, plate tectonics and RRR-triple-junctions would give you the mechanism you require for splitting a supercontinent into two (google the formation of the atlantic ocean for less technical references), and the final trench closure prior to the formation of pangaea-esque supercontinents also provides a similar geography.

EDIT.

by ocean i mean not a sprawling one like earth has but more like a strip spanning either along the equator or along the meridian.

How much "mostly land" are we talking about then? Your continents are fully separated by water right? If you wish to maintain a vaguely earth-like biome you'll need large oceans to act as a reservoir for rainwater. Even then, the interior of supercontinents is INCREDIBLY dry due to water sources being a long way away (rainclouds exhaust water prior to reaching the central interior). If the planet you're thinking of is 75%-80% land it will be very very very dry and desertlike.

Regardless, the plate tectonics I outline above are unchanged (barring some technical details about dewatering reactions' importance in lowering mantle viscosity near trenches). You can totally have the scenario you describe. If the oceans are very small you might have exposed basalt (Earth's oceanic plates) between the continents -- which seem to rise above the basalt plains like high mesas.

Well it does not have to have rainforests and the like. I envisioned a landscape akin somewhat to Iceland. with forests and the like but also with big open plains with a lot less growth and the higher places wich are mostly barren. — Blue Devil, Nov 14 '18 at 21:18
Cool. Well you can get that, but it won't be the whole planet. It is very hard to overstate how stubborn the desert problem is.
You could have an equatorial ocean on a cool planet, with habitable zones extending a few hundred km from the ocean until you hit deserts and punishing seasons (oceans act as a heat buffer, giving cool summers and warm winters. The centre of a continent gets crazy hot and crazy cold. Think a 60C/140F swing from winter to summer). — Mark_Anderson, Nov 14 '18 at 21:28
A north-south ocean give more complex weather patterns, but the overall pattern of brutally dry continental centres with large temperature swings remains in place. — Mark_Anderson, Nov 14 '18 at 21:28
So basically the only way to avoid the desert would be to have earth like continents with ocean all around them? — Blue Devil, Nov 14 '18 at 21:49
Pretty much. You need a way for the rain to get into the continental interiors, and that means have a large body of static water whose evaporation is the sourcing point for clouds.
You can use oceans, large lakes, or an extended area of swampland that doesn't drain away, but ultimately it's all some version of getting a constant body of water near the continental interiors. — Mark_Anderson, Nov 15 '18 at 21:25

score 1 · Answer 2 · answered Nov 17 '18 at 03:14

Equatorial is more plausible

Assuming your planet is rotating, the Coriolis effect will attempt to drive waters in the northern and southern hemisphere in the clockwise and anti-clockwise direction, respectively.

Therefore, the meridinal ocean will tend to erode its Eastern shore in the Northern hemisphere, and its Western shore in the Southern hemisphere. This erosion wouldn't be immediate, but it would be significant over geological time.

Therefore, the equatorial ocean is more plausible as a long term geological formation.

Equatorial or Meridial Ocean

2 Answers2

Equatorial is more plausible