The Expanding earth theory is an attempt to explain the position and movement of continents on the surface of the Earth. It has a relatively small following today, compared with the almost universally accepted theory of plate tectonics, and is considered to be discredited by mainstream geologists.
An expanding earth model was developed in the 1960s, building upon emerging evidence for sea floor expansion and continental drift. The expanded earth theory (and plate tectonics) incorporates the appearance of new crustal material at mid-ocean ridges, but the process of subduction is largely absent in this model.
Very few geologists or geophysicists today support the expanded Earth.[1] Many of those that remain are proponents of the ideas of the late Australian geologist S. Warren Carey. While Carey's ideas were popular for a time in the 1950s and 1960s, most workers in earth science believe that evidence collected over the last several decades supports a fixed size Earth, due to subduction, over the expanded Earth.
Stumbled upon this video last night. One of the most fascinating theories I've ever come across

watch it.