How is the composition of Earth's present-day mantle used to ...

[urbanoutfitters]

How is the composition of Earth's present-day mantle used to support the magma-ocean hypothesis?
 
  What will be an ideal response?

Question 2

What evidence supports the hypothesis that Earth's early atmosphere (before 2.3 billion years ago) did not contain oxygen?
 
  What will be an ideal response?

[Koolkid240]

Answer to Question 1

The fact that the composition of Earth's present day mantle is poor in strongly iron-seeking elements, rich in slightly iron-seeking elements and has intermediate concentrations of moderately iron-seeking elements is consistent with the magma-ocean hypothesis.

Answer to Question 2

The Precambrian iron-ores of the U.S. Great Lakes Region, South America, and Australia indicate the lack of oxygen during early Earth history. These iron ores are peculiar chemical sedimentary rocks that cannot form from water that contains oxygen (as the modern oceans do).

[urbanoutfitters]

Thanks for the timely response, appreciate it

[aliotak]

Excellent