Look at a map and the coastlines on either side of the Atlantic seem to fit like puzzle pieces. A meteorologist argued that the continents were once joined and have drifted apart, but the geologists of his day rejected the idea for decades, insisting no force could move a continent. Do continents really move?
Sign in and pick a handle to post claims, evidence and rebuttals, and to vote.
Continents really do move. Continental drift grew into plate tectonics and now underpins all of earth science.
In the 1950s and 60s, seafloor spreading (new crust forming at mid-ocean ridges) and magnetic stripes in seafloor rock revealed the mechanism that carries continents — mantle convection and plate motion — and the debate was settled.
Shared fossils can be explained by land bridges that linked continents and later sank beneath the sea.
✦ Source needed
There is no need to move whole continents to explain shared fossils.
✦ Source needed
One continent splitting apart is simpler and fits the data better than land bridges.
✦ Source needed
Computed from the vote distribution. It is an observation, not a verdict on which claim is right.
Proponents argue that fitting coastlines, matching rock strata, identical freshwater fossils across oceans, and past climate anomalies point to a single original supercontinent. In contrast, it is suggested that shared fossils could be explained by sunken land bridges rather than moving continents, which proponents counter lacks geological evidence.
Open points
Next questions
The continents scattered across the globe today were once a single supercontinent, Pangaea, which broke apart and drifted slowly to their present positions.
The east coast of South America and the west coast of Africa interlock like puzzle pieces — not just the shorelines but the continental shelves. That is far too precise to be coincidence.
The two continents split by the Atlantic carry the same rock strata of the same age and the same fossils — Mesosaurus, a freshwater reptile, among them. A creature that could not cross an ocean turning up on both shores means the shores were once joined.
The shared fossils are just as well explained by land bridges that once linked the continents and later sank beneath the sea. There is no need to move whole continents.
Skeptics argue that no known physical force could push solid continental granite through harder oceanic crust. Proponents respond that continents do not plow through crust, but instead ride on thermal mantle convection currents, citing observed seafloor spreading at mid-ocean ridges as direct evidence of the mechanism.
Open points
Next questions
Continents do not move. Drift has no source for the force it would take to push a continent anywhere.
There is no trace anywhere of continent-sized land bridges sinking without leaving a mark. One continent splitting apart is far simpler and fits the data better.
Near the equator we find scars gouged by thick glaciers, while close to the poles we find tropical plant fossils and coal seams. It all adds up if the continents once sat in different climate zones and then moved.
A slab of solid granite plowing through oceanic crust that is harder still is physically impossible. Nothing anyone has calculated could supply such a force.
The continent is not "plowing" through anything. If thermal convection in the mantle carries the crust along like a conveyor belt, continents ride with it rather than crashing into it.
And we have now observed it: new seafloor forms at mid-ocean ridges and spreads outward to either side. The engine that carries continents is measured, not imagined.