Author Question: True or False: Earth exhibits a gradual inward transition from low-density to high-density rock. ... (Read 129 times)

nelaaney · **on:** Jul 16, 2018

True or False: Earth exhibits a gradual inward transition from low-density to high-density rock.

Indicate whether this statement is true or false.

Question 2

How did the hydrosphere and atmosphere form?

What will be an ideal response?

mk6555 · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

Answer: FALSE

Answer to Question 2

Answer: Two contrasting hypotheses explain the origin of Earth's atmosphere and hydrosphere. One hypothesis suggests delivery of water-rich materials from meteorites and comets that accreted to the initially dry Earth very late in the formation of the planet. The other hypothesis suggests that Earth accreted wet, from planetesimals or embryos already containing water-bearing minerals. Water vapor is the most abundant gas erupted from volcanoes. This observation is consistent with the hypothesis that the hydrosphere derived from melting water-bearing mantle minerals and erupting water vapor through volcanoes. Atmosphere composition changed through Earth history as a result of weathering reactions and the presence of photosynthetic organisms, which consume carbon dioxide and create oxygen.