Earth Sciences for Civil Engineering Assignment 1

Quaternary Period

• Consists of two epochs: Holocene and Pleistocene.
• The Holocene is the most recent epoch, while the Pleistocene preceded it.

Supernova Explosion

• Occurred approximately 7 billion years ago.
• Marks a significant astronomical event.

Magma and Oceanic Crust

• New oceanic crust forms at mid-oceanic ridges.
• Created by mantle upwelling in response to plate separation, where magma rises and cools to form lithosphere.

Ocean Ridge System

• Encompasses a continuous belt of 65,000 km, recognized as the longest mountain range on Earth.
• Mid-Atlantic Ridge is a notable example, bisecting the Atlantic Ocean.

Earth's Internal Structure

• Seismic waves reveal two core layers: the outer core is liquid, while the inner core is solid.
• Inner core consists of iron and nickel, with extreme temperatures reaching up to 5,500°C.

Density and Isostasy

• Low-density rocks float higher and possess deep roots; high-density rocks float lower with shallow roots.
• Isostasy governs the buoyancy and equilibrium of the Earth's lithosphere.

Principle of Isostasy

• Governs the rise or subsidence of the Earth's crust until it achieves buoyant balance.
• Crucial for understanding geological stability and changes.

Geodynamo System

• Involves interactions between the inner and outer core.
• Generates the Earth's magnetic field through convection currents of fluid metal in the outer core, influenced by heat from the inner core.

Magnetic Field Generation

• The heat from the outer core causes convection, vital for maintaining the Earth's magnetic field.
• Organized by the Coriolis force, leading to circulating electric currents.

Lehmann Discontinuity

• Marks the boundary between the outer and inner core.
• Characterized by an abrupt increase in P-wave and S-wave velocities at around 220 km depth.