Question

Which of the following statements are valid for Tectonic plates

1. Include the crust and the uppermost mantle

2. Are the outermost shell of the solid earth?

3. Are a rigid, solid layer about 100 km thick? 
1. Only 1 
2. 1 and 2 
3. 2 and 3 
4. 1, 2 and 3

Answer 1

Correct Answer - Option 4 : 1, 2 and 3

Concept:

Crust

• The Earth’s crust is the outermost layer and is the most familiar since people live on the outer skin of the crust. It is rigid, brittle, and thin compared to the mantle, inner core, and outer core. Because of its varying characteristics, this outer layer is divided into continental and oceanic crusts.

Mantle

• Earth’s mantle lies beneath the crust and above the outer core, averaging about 1802 miles (2900 km) thick and representing 68.3% of the Earth’s mass 84% of Earth’s volume. A transaction zone divides this layer into the upper and lower mantles.

Earth’s Core

• Using the seismic data, the scientists had first postulated the existence of a fluid core. In 1915, Gutenberg published a measurement of the core’s radius.
• In 1936, Danish seismologist Inge Lehmann (1888 – 1993) presented a paper titled, “P’” (or P – Prime, after the seismic waves), which announced the discovery of Earth’s inner core. The division between the inner and outer core is now called the Lehmann discontinuity.

Outer Core

• The liquid outer core is a layer between 2885 and 5155 km deep in the Earth’s interior. It is thought to move by convection (the transfer of heat through the circulating motion of materials), with the movement possibly contributing to the Earth’s magnetic field. The outer core represents about 29.3% of the Earth’s total mass.

Inner Core

• The inner core is thought to be roughly the size of the Earth’s Moon. It lies at a depth, 5150 km to 6370 km beneath the Earth’s surface and generates heat close to the temperature on the sun’s surface.
• It represents about 1.7% of the Earth’s mass and is thought to be composed of a solid iron-nickel alloy suspended within the molten outer core.

Plate Tectonic

• The theory of plate tectonics proposes that the earth’s lithosphere is divided into 7 major and several minor plates. The movement of the plates results in the building up of stresses within the plates and the continental rocks above, which leads to folding, faulting, and volcanic activity. The major plates are surrounded by Fold Mountains, ridges, trenches, and faults.
• Tectonic plates include the crust and the uppermost mantle
• They are the outermost shell of the solid earth and a rigid, solid layer about 100 km thick.