Most of the land is in the Northern Hemisphere by luck. The continents are in motion on the surface of the Earth in a process called tectonics. The continents are part of tectonic plates, which are pieces of the Earth's outer shell that sometimes move away from each other and sometimes crash into each other. At several times in the past, most of the continental crust was attached. As they moved around, the continents broke apart from each other. What we now have in the Northern Hemisphere is a result of these tectonic motions.