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What happened to the tides when the Earths continents were all Pangaea?
Question Date: 2009-09-08
Answer 1:

First, a little background on tides
Tides are caused primarily by the pull of the moons gravity on the oceans. This causes the surface of the ocean to bulge on the side of the Earth closest to the moon. On the opposite side of the Earth, inertia (the tendency for a moving object to continue moving in a straight line) causes the water to bulge outwards on that side as well. These bulges correspond to high tides, whereas the relatively lower surfaces between the two bulges correspond to low tides. Because the Earth rotates through two tidal bulges each day, we experience two high tides and two low tides each day.

If the Earth were completely covered by water without any continents, the bulges would simply move westward around the world. However, the continents block such a movement of the tides and create complex patterns of tides within each ocean basin. Most places on Earth experience two high and two low tides per day. If these tides are about the same height, it is known a semidiurnal tide. Most coastlines along the Atlantic Ocean experience a semidiurnal tide. If the high and low tides have different heights, i.e. one high tide is higher than the other, this is known as a mixed-semidiurnal tide. Mixed-semidiurnal tides are common in the Pacific Ocean. A few places, such as the Gulf of Mexico, have only one high tide and one low tide each day. This is known as a diurnal tide. What kinds of patterns develop in a given basin depends on the size and shape of the ocean basin. The tides you see at a particular location also depend on the local geometry of that coastline.

NOAA has a good website for learning about tides:


Now, to answer the question

About 250 million years ago, the continents were arranged into one supercontinent known as Pangaea, surrounded by a global ocean known as Panthalassa. Paleoceanographers (scientists who study the oceans of the past) modeled what the tides would have been like in this ocean [1]. They found that, like Pacific Ocean of today, Panthalassa would have had mixed semidiurnal tides. Apparently this pattern of tides is able to develop in wide oceans basins such as the Pacific Ocean or Panthalassa (even wider) better than in the more confined Atlantic Ocean basin. Additionally, they concluded that the height of the tides in Panthalassa would have been a slightly larger than today.

[1] Archer, A. W. (1996), Panthalassa: Paleotidal Resonance and a Global Paleocean Seiche, /Paleoceanography/, 11(5), 625632.

Answer 2:

Well nothing much happened specifically... the basic astronomic forcing remained the same. the run up of the ocean tides does depend on the precede configuration of the continents , the depth of the ocean basins and the coastline/topography...so no doubt all these factors came into play... but the detailed coastline configurations are not something we will ever have much info about...

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