The “climate theory” of dinosaur extinction is one that many scientists believe is more feasible than most other theories. One of the theories of gradualism is that the movement of continents over millions of years brought about changes in Earth’s climate, including the changing of oceanic currents; spreading of deserts; drying up of inland seas; shifts in Earth’s axis, orbit, or magnetic field; spreading of polar ice caps; and the increase in volcanic eruptions. The resulting slow climate changes (from either one, several, or all of the above events) caused the gradual decline of the dinosaurs. They could not evolve quickly enough to compensate for the changes.