Does the Northern Hemisphere have more mass?
The vast majority of Earth’s land masses are located north of the Equator. How can that be, and has it always been like that?
The distribution of land masses on Earth is the result of plate tectonics – motions in Earth's upper layer. The most important driver of plate tectonics is heat flows in Earth’s interior, that make the large continental plates move under each other and sink into Earth. However, there is no indication that plate tectonics favour one hemisphere over the other concerning land mass.
The distribution is constantly changing. Now, the Northern Hemisphere includes 39 % land as compared to 19 % in the Southern Hemisphere, but 200 million years ago, the land masses were mainly located in the Southern Hemisphere.
And new change is on its way. The motions of the continental plates indicate that over the next 100 million years, the continents will collect in the Northern Hemisphere into a supercontinent consisting of North America, Europe, Asia, Africa, and Australia.