Figure 3 – Convection currents in the mantle portion of the Earth

the Earth as shown in figure 3. The cause of the origin of these currents is the presence of radioactive elements which causes thermal differences in the mantle portion. Holmes argued that there exists a system of such currents in the entire mantle portion. This was an attempt to provide an explanation to the issue of force, on the basis of which contemporary scientists discarded the continental drift theory.