Study the diagram showing the range of temperature in the Earth’s layers. Graph of Temperature of Earth apostrophe s Layers, showing start depth at 410 kilometers and start temperature at 1,000 degrees Celsius. As depth increases to 6,370 kilometers, temperature increases to over 6,000 degrees Celsius. What does the diagram show about Earth’s interior? The outer core is the hottest region. The mantle is hotter than the outer core. The continental crust is the coolest region. The inner core is cooler than the lithosphere.