Earth's Internal Heat and Geological Manifestations

1. Internal Manifestations of the Earth

Inside Temperature of the Earth

Although the surface is cold, scientists have calculated that at 2,000 km, the temperature exceeds 2,500 °C, and at 6,300 km in the Earth's core, it is about 4,500 °C.

Consequences of Heat Loss

The Earth gives off heat to the outside as magma. Magma is formed by molten rock found at high temperatures. When it reaches the surface, it forms volcanoes.

2. Volcanoes

Formation of Volcanoes

Volcanoes form when magma rises to the surface. During eruptions, explosions occur, which expel gas from the magma.

Materials Emitted by Volcanoes

In eruptions, the volcano emits:

• Gases: They help the lava exit.
• Lavas: Liquids that are ejected by volcanoes.
• Pyroclasts: These are classified as volcanic bombs (reaching 30 cm), lapilli, and ash (very fine and light).

3. Earthquakes

Nature of Earthquakes

Earthquakes are the shaking of the ground, generally lasting from a few seconds to a few minutes.

Why Do Earthquakes Occur?

• Tectonic earthquakes: These are produced by the breaking or tearing of rocky bodies.
• Volcanic earthquakes: These are produced by underground movement or volcanic eruptions when they are very explosive.

Seismographs

The waves produced during earthquakes are transmitted through the interior of the Earth. In seismological institutes, they are captured by highly sensitive instruments called seismographs and are recorded in a graph called seismograms.

4. Magmatic Rocks

Plutonic Rocks

These rocks are formed when magma solidifies within the Earth. If they are found in large masses, they are called plutons.

Subvolcanic Rocks

These rocks are formed when magma rises to the surface through fractures or cracks and solidifies inside, forming thin rock masses.

Volcanic Rocks

These rocks are created when magma reaches the surface and solidifies into extensive layers called lava flows.

Sound Characteristics

Note: This section describes physical properties of sound.

• Intensity: Or volume; the feature that makes us distinguish between strong and weak sound.
• Tone: The feature distinguishing sharp sounds from bass sounds.
• Timbre: The characteristic that distinguishes two sounds of the same pitch and intensity.

5. Metamorphic Rocks and Cordilleras

Metamorphic Rocks

Metamorphic rocks are derived from other rocks that change when they are affected by hot magma. The process that generates them is called metamorphism.

The Ranges (Cordilleras)

The ridges are mountain ranges formed by igneous, sedimentary, and metamorphic rocks. Cordilleras are created when two plates collide. The process varies depending on the colliding plates (e.g., when an oceanic plate and a continental plate collide, or where continental plates collide).