Please take out your science notebooks. Date: Monday, 9/24/12 Title: How Scientists Make Inferences about Earth’s Interior Observations: We have seen volcanoes spew out hot fiery lava from beneath the Earth’s surface. As you descend deeper into a mine, the temperature increases. Inference: The interior of Earth is hot! Observations: (Refer to p. 21 in your text.) Scientists have calculated the mass of the Earth based on the formula for gravity, which depends on the mass of the objects and the distance between them. We can calculate the volume of Earth from the formula for the volume of a sphere, Volume = (4\3) (3.14) (r3). (Refer to your planners) Knowing the mass and volume of Earth, the density of the Earth can be determined. The density of the Earth is greater than the density of the granite and basalt that make up most of the crust. Inference: The core is denser than the crust. Density of the entire planet Earth = 5.5 g/cm3. Density of granite and basalt = 2.5 – 3.0 g/cm3. Observations: The origin of concentric (having a common center) layeringthe Earth is stratified into layers by density (heavy core, intermediate mantle, light lithosphere). Inference: We infer that early in its history the earth went through a molten stage that led to the heavy materials sinking inward to form the core. Observations: Seismic waves are waves produced by earthquakes: -p waves travel through solids and liquids. -s waves travel only through solids. Not all seismograph stations receive p and s waves from an earthquake. Inference: A layer of the Earth is liquid.