Some cratons in Canada and Greenland shelter the oldest continental rocks in the world, about 4 billion years old. Other cratons in South Africa, Australia and Asia have continental rocks that are 3 billion years old. The oldest seafloor is comparatively very young, approximately 280 million years old.
B: China and India both have a population around 1.5 billion people so in total they have around 3 billion people combined! That is more than the continent of Africa and North America combined!
