Structure and Atmosphere of Earth
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Across: 3. Process required by plants for growth 6. A noble gas 7. These currents occur in the mantle 8. Names used to describe a plate of the Earth 9. These gave rise to an increase of oxygen levels in the atmosphere 10. Earthquakes and volcanoes occur at these regions of tectonic plates 11. These released carbon dioxide, water vapour and nitrogen 13. This is approximately 3000 km thick, below the crust 14. Gas released during photosynthesis 15. Organisms that release oxygen 16. Gases in group 0 in the atmosphere.
Down: 1. Very dense part of Earth, mainly consisting mainly of nickel and iron. 2. Earth's crust and upper part of the mantle. 4. Outer part of the earth, between 5km to 70 km thick. 5. A noble gas found in the atmosphere. 12. The most common gas found in the atmosphere,