# Inference: The interior of Earth is hot!

```Please take out your
science notebooks.
Date:
Monday, 9/24/12
Title:
How Scientists Make Inferences
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).
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.
```