Background: The theory of plate tectonics demonstrates that the continents of the Earth are moving across the surface at the rate of a few centimeters per year. This is expected to continue, causing the plates to relocate and collide. Continental drift is facilitated by two factors: the energy generation within the planet and the presence of a hydrosphere. With the loss of either of these, continental drift will come to a halt. The production of heat through radiogenic processes is sufficient to maintain mantle convection and plate subduction for at least the next 1.1 billion years.At present, the continents of North and South America are moving westward from Africa and Europe. Researchers have produced several scenarios about how this will continue in the future. These geodynamic models can be distinguished by the subduction flux, whereby the oceanic crust moves under a continent. In the introversion model, the younger, interior, Atlantic ocean becomes preferentially subducted and the current migration of North and South America is reversed. In the extroversion model, the older, exterior, Pacific ocean remains preferentially subducted and North and South America migrate toward eastern Asia.As the understanding of geodynamics improves, these models will be subject to revision. In 2008, for example, a computer simulation was used to predict that a reorganization of the mantle convection will occur over the next 100 million years, causing a supercontinent composed of Africa, Eurasia, Australia, Antarctica and South America to form around Antarctica.Regardless of the outcome of the continental migration, the continued subduction process causes water to be transported to the mantle. After a billion years from the present, a geophysical model gives an estimate that 27% of the current ocean mass will have been subducted. If this process were to continue unmodified into the future, the subduction and release would reach an equilibrium after 65% of the current ocean mass has been subducted.

Situation: Two friends were in college. Hank studied plate tectonics, while his buddy Alex studied Earth's atmosphere. They were both very fascinated by the subjects.

Question: Which student learned more about the continents of Earth?
Answer: Hank

Situation: Two friends were in college. Hank studied plate tectonics, while his buddy Alex studied Earth's atmosphere. They were both very fascinated by the subjects.

Question: Which student learned less about the continents of Earth?
Answer: Alex

Situation: Two friends were in college. Hank studied plate tectonics, while his buddy Alex studied Earth's atmosphere. They were both very fascinated by the subjects.

Question: Which student learned less about Continental drift?
Answer: Alex

Situation: Two friends were in college. Hank studied plate tectonics, while his buddy Alex studied Earth's atmosphere. They were both very fascinated by the subjects.

Question: Which student learned more about Continental drift?
Answer: Hank

Situation: Two friends were in college. Hank studied plate tectonics, while his buddy Alex studied Earth's atmosphere. They were both very fascinated by the subjects.

Question: Which student learned more about the production of heat through radiogenic processes?
Answer: Hank

Situation: Two friends were in college. Hank studied plate tectonics, while his buddy Alex studied Earth's atmosphere. They were both very fascinated by the subjects.

Question: Which student learned less about the production of heat through radiogenic processes?
Answer: Alex

Situation: Two friends were in college. Hank studied plate tectonics, while his buddy Alex studied Earth's atmosphere. They were both very fascinated by the subjects.

Question: Which student learned less about mantle convection?
Answer: Alex

Situation: Two friends were in college. Hank studied plate tectonics, while his buddy Alex studied Earth's atmosphere. They were both very fascinated by the subjects.

Question: Which student learned more about mantle convection?
Answer: Hank

Situation: Two friends were in college. Hank studied plate tectonics, while his buddy Alex studied Earth's atmosphere. They were both very fascinated by the subjects.

Question: Which student learned more about plate subduction?
Answer: Hank

Situation: Two friends were in college. Hank studied plate tectonics, while his buddy Alex studied Earth's atmosphere. They were both very fascinated by the subjects.

Question: Which student learned less about plate subduction?
Answer: Alex