A mantle weak enough for convection is also weak enough to

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show zonal effects due to the earth's rotation. Zonal rotation--or equatorial acceleration--in a plastic mantle, underneath "rigid" crustal blocks, should have certain specific results.

For instance, major continental blocks in the Northern Hemisphere should, over the long term, describe counterclockwise loops. North America has had such a path, as has Europe. Present motions along the rim of the Pacific Ocean suggest that the North Pacific plate also has been following a counterclockwise loop.

Major continental blocks in the Southern Hemisphere should describe clockwise loops. This has been the pattern for Antarctica, Australia, and South America. Africa, located primarily in the Southern Hemisphere during Paleozoic time, traced a clockwise loop during that era; in Cenozoic time, largely in the Northern Hemisphere, it has been moving with counterclockwise curvature.

Further, major blocks close to the equator should have a greater west-to-east acceleration than major blocks located far from the equator. Hence, South America should be moving eastward relative to North America, and Africa should be moving eastward relative to Europe, North America, and South America. The northward paths of Europe and North America, relative to Africa and South America, also indicate major tensional effects in the Mediterranean and Gulf of Mexico-Caribbean areas.

The Northern Pacific block should be moving eastward faster than the North American block as it is closer to the equator, and should be turning in a counterclockwise sense. This movement provides a north-south zone of east-west compression along the western edge of North America and down the East Pacific Rise.

Reconstruction of block paths indicates that Gondwanaland, a hypothetical Paleozoic supercontinent, was more likely a convergence of individual blocks which had separate previous histories.

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