what is the least dense layer of the earth

MSN: What Are The Layers Of Earth Made Of - Explained By Earth Scientists Earth's crust ranges from 5 to 70 kilometers in thickness and serves as the planet's outermost layer. This thin shell represents less than one percent of Earth's total mass, yet it's the only layer we ... What Are The Layers Of Earth Made Of - Explained By Earth Scientists Prefer Newsweek on Google to see more of our trusted coverage when you search. Earth's inner layers have just got a bit more complicated, with scientists discovering a whole new inner core within the ... least meaning, definition, what is least: less than anything or anyone else: Learn more.