Which single piece of evidence most directly supports the idea that continents were once connected?

• A. Matching fossil types across continents
• B. The fit of continental coastlines when the continents are drawn together
• C. Identical radiometric ages of rocks on different continents
• D. Similar climates indicated by fossil plant distributions

Answer: (B)

Continents moving over time leave physical clues about how they were arranged in the past. The most direct piece of evidence that they were once joined is that the edges of the continents line up like puzzle pieces when you try to fit them together. This coastlines-fit suggests they were one larger landmass that later split apart as the tectonic plates moved.

Other hints, such as fossils found on now-distant continents, rocks with similar ages, or ancient climates that appear alike in different places, support the idea of a connected past but don’t show the land’s actual shape as clearly.