Engineering geology

Plate Tectonics in the Future

Geologists have extrapolated present-day plate movements into the future. Figure 1 illustrates where Earth’s landmasses may be 50 million years from now if present plate movements persist during this time span. In North America we see that the Baja Peninsula and the portion of southern California that lies west of the San Andreas Fault will have slid past the North American plate. If this northward migration takes place, Los Angeles and San Francisco will pass each other in about 10 million years, and in about 60 million years the Baja Peninsula will begin to collide with the Aleutian Islands.

If Africa continues on a northward path, it will continue to collide with Eurasia. The result will be the closing of the Mediterranean, the last remnant of a once-vast ocean called the Tethys Ocean, and the initiation of another major mountain-building episode (see Figure 1). Australia will be astride the equator and, along with NewmGuinea, will be on a collision course with Asia. Meanwhile, North and South America will begin to separate, while the Atlantic and Indian Oceans will continue to grow, at the expense of the Pacific Ocean.

Figure 1 – The world as it may look 50 million years from now This reconstruction is highly idealized and based on the assumption that the processes that caused the breakup of Pangaea will continue to operate.

A few geologists have even speculated on the nature of the globe 250 million years in the future.
In this scenario the Atlantic seafloor will eventually become old and dense enough to form subduction zones around much of its margins, not unlike the present-day Pacific basin. Continued subduction of the floor of the Atlantic Ocean will result in the closing of the Atlantic basin and the collision of the Americas with the Eurasian–African landmass to form the next supercontinent, shown in Figure 2.

Figure 2 – Earth as it may appear 250 million years from now

Support for the possible closing of the Atlantic comes from a similar event, when an ocean predating the Atlantic closed during Pangaea’s formation. Australia is also projected to collide with Southeast Asia by that time.
If this scenario is accurate, the dispersal of Pangaea describe changes in the positions of the continents if we assume that the plate motions we see today continue 50 million years into the future.
Such projections, although interesting, must be viewed with considerable skepticism because many assumptions must be correct for these events to unfold as just described. Nevertheless, changes in the shapes and positions of continents that are equally profound will undoubtedly occur for many hundreds of millions of years to come. Only after much more of Earth’s internal heat has been lost will the engine that drives plate motions cease.

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