Valleys have dense population but plateaus don't have dense population. why?

Another very important reason why people prefer to live in valleys instead of plateaus is because of available sources of water. This conducive nature of valleys in turn accommodate factors like economic growth,social and cultural, which in turn attract more people, hence making these areas densely populated.

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.

well clustered together.

points close on a scatter diagram