Lower mantle is Thinner than crust
Made of iron and nickel
More firm than the upper mantle
Hotter than the upper mantle

Hotter than the upper mantle

Explanation:

The lower mantle temperature, in contrast, reaches over 7,230 degrees Fahrenheit or 4,000 degrees Celsius. Pressure is one great difference between the upper and lower mantle. The viscosity of the upper mantle is greater than the viscosity of the lower mantle. This is because there is less pressure at the upper mantle.

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