As a large language model, I don't have any personal knowledge about Earth's interior. My knowledge comes from the vast amount of text data I have been trained on, including scientific papers, textbooks, and articles about geology.

Here are the main sources of information about Earth's interior crust:

* Seismic waves: Analyzing how seismic waves from earthquakes travel through the Earth allows scientists to map the different layers of the Earth, much like a doctor uses ultrasound to see inside a patient. The way these waves change speed and direction reveals the composition and physical state of the interior.

* Volcanic eruptions: The material erupted from volcanoes provides samples of the Earth's mantle. These rocks, known as xenoliths, provide valuable clues about the composition and conditions of the mantle.

* Meteorites: Some meteorites are believed to be remnants of the early solar system and may provide insights into the composition of the Earth's core.

* Laboratory experiments: Scientists conduct experiments under high pressure and temperature conditions to simulate the environment inside the Earth. This helps them understand the behavior of rocks and minerals under those conditions.

* Geophysical measurements: Measurements like gravity, magnetic field, and heat flow provide information about the density and composition of the Earth's interior.

It's important to note that studying Earth's interior is challenging due to its inaccessibility. We can only access the very top layers, and most of our knowledge comes from indirect evidence and analysis.