The earth is about 4.6 billion years old. Based on observations of your seafloor spreading model, why do you think that the oldest ocean floor is only about 200million years old?
Answers
Answer:
1. Because earth is in constant motion. The plates are in constant motion, most oceanic plates are subducted into the mantle to generate magma thus older oceanic plates will subduct beneath the younger ones due to density differences.
Explanation:
Oceanic crust is constantly being created as the plates pull apart. The fact that the oldest part is 200 million years old just shows that that area is 200 million years old. It doesn’t say anything about the rock that’s not under the water.
Meanwhile we have these things called “cratons” which are for lack of a better word the most ancient and solid rock that continents sit upon. The oldest one is the Kaapvaal Craton in the southern part of Africa. It’s dated to between 3.6–2.5 billion years ago. It’s literally some of the oldest rock we have and was part of the earliest supercontinent Vaalbara.