Africa is called a "plateau continent" because much of the land is raised well above sea level, dropping off sharply near the coastline. Additionally, Africa's continental shelf drops off precipitously, providing deep harbors but limiting offshore resource exploitation.
Africa's plateau structure is largely due to its existence on a single tectonic plate. Most of the continent is flat and, despite faults in some areas, free of mountains generated by tectonic collision. The Olduvai Gorge may be the single place where Africa is partially on another tectonic plate, but even this is disputed by geologists.
The unique geography of Africa has historically prevented the use of most waterways as transportation routes for large vessels, limiting the development of trade for millennia. However, as of 2014, the waterways provide inexpensive hydroelectric power.