Science Olympiad Dynamic Planet Practice Test

How does temperature change with depth in the Earth's crust?

1. It decreases as you go deeper

2. It remains constant throughout

3. It increases with depth

4. It varies unpredictably

The correct answer is: It increases with depth

Temperature in the Earth's crust generally increases with depth due to the geothermal gradient, a phenomenon resulting from the heat produced by radioactive decay of minerals, as well as residual heat from the formation of the planet. This means that as you descend into the Earth, you encounter higher temperatures because the heat has no escape and accumulates in the denser layers of rock. On average, the temperature can increase roughly 25 to 30 degrees Celsius for every kilometer you descend, although this can vary based on geological conditions, such as the type of rock and the presence of fluids. Understanding this gradient is crucial for geologists and helps explain various geological processes, such as the formation of metamorphic rocks and volcanic activity. The other options do not accurately reflect the behavior of temperature with depth in the Earth's crust: the temperature does not decrease, does not remain constant, and while there may be localized variations due to geological features, it does not vary unpredictably on larger scales. Thus, the statement that temperature increases with depth is consistent with established geological principles.