Which of the following is evidence that supported early continental drift proposals?

Which of the following is evidence that supported early continental drift proposals?

• A. Matching coastlines across continents
• B. Differences in ancient climates
• C. Disparate rock types on separated continents
• D. Distinct current ocean depths

Answer: (A)

Matching coastlines across continents show that landmasses could have been joined in the past. When you put the edges of continents like South America and Africa together, they fit like puzzle pieces, suggesting they were once one continuous land surface. This visual alignment gave scientists a powerful, intuitive reason to propose that continents had moved apart over time. Over time, other clues—like similar fossils found on now-separated continents, matching rock formations, and evidence of ancient climates (such as glacial deposits in locations that are now tropical)—also supported the idea, but the coastline fit was the clearest early signal that continents weren’t always in their present positions. The other options don’t provide as direct a link to past connected land. Differences in ancient climates can support the idea when considered with other evidence, but they don’t show a concrete face-to-face connection like coastlines do. Current ocean depths are measurements of today’s oceans and don’t by themselves reveal how continents moved in the geological past. And having different rock types across separated landmasses would argue against a single, shared landmass rather than support its existence.

Matching coastlines across continents show that landmasses could have been joined in the past. When you put the edges of continents like South America and Africa together, they fit like puzzle pieces, suggesting they were once one continuous land surface. This visual alignment gave scientists a powerful, intuitive reason to propose that continents had moved apart over time.

Over time, other clues—like similar fossils found on now-separated continents, matching rock formations, and evidence of ancient climates (such as glacial deposits in locations that are now tropical)—also supported the idea, but the coastline fit was the clearest early signal that continents weren’t always in their present positions.

The other options don’t provide as direct a link to past connected land. Differences in ancient climates can support the idea when considered with other evidence, but they don’t show a concrete face-to-face connection like coastlines do. Current ocean depths are measurements of today’s oceans and don’t by themselves reveal how continents moved in the geological past. And having different rock types across separated landmasses would argue against a single, shared landmass rather than support its existence.