Question

Which term refers to sections of Earth's crust and part of the upper mantle? A. asthenosphere C. lithosphere B. plate D. core

Short answer

B. Plate refers to sections of Earth's crust and part of the upper mantle.

Step-by-step solution

Understand the Problem

The problem asks us to identify which term refers to sections of Earth's crust and part of the upper mantle. We need to understand the structure of the Earth to address this.

Define Each Option

We have four options to choose from: A. Asthenosphere - This is a semi-fluid layer upon which tectonic plates move. B. Plate - These are segments or sections of Earth's crust and part of the upper mantle found on top of the asthenosphere. C. Lithosphere - This comprises the rigid outer layer of the Earth, including the crust and the upper mantle. D. Core - This is the innermost layer of the Earth, not related to the crust and upper mantle.

Analyze the Options

- The lithosphere consists of the crust and the uppermost mantle and is divided into tectonic plates. - The term "plate" refers to the sections of the lithosphere separated by boundaries. - The asthenosphere is not a section of the crust and upper mantle but a layer below them. - The core refers to the inner parts of the Earth, which are unrelated to the crust.

Choose the Correct Answer

Considering the information, 'Plate' most directly refers to sections of Earth's crust and part of the upper mantle. The lithosphere describes the rigid outer layer, but 'Plate' specifically mentions sections of it.

Key concepts

Earth's Crust

The Earth's crust forms the outermost shell of our planet. It is relatively thin compared to other layers and can be classified into two types: continental and oceanic crust.
The continental crust is thicker, ranging between 30 to 70 kilometers, and mostly composed of light-colored, granitic rocks. The oceanic crust, on the other hand, is thinner, about 5 to 10 kilometers thick, and primarily made up of dark, basaltic rocks.

• The crust is where we live and is critical for supporting life, providing essential resources like minerals and soil.
• It is also the place where tectonic activity occurs, such as earthquakes and volcanic eruptions.

Understanding the Earth's crust helps us learn about the dynamic processes of our planet and how they shape the environment.

Upper Mantle

Sitting directly beneath the Earth's crust, the upper mantle spans up to about 660 kilometers deep. This region of the Earth is part of the mantle, which extends further down to about 2,900 kilometers.
The upper mantle, together with the crust, forms the lithosphere. This part of the mantle is slightly plastic, allowing it to facilitate the movement of tectonic plates.

• The upper mantle is composed primarily of silicate minerals, such as olivine and pyroxene.
• Its semi-solid state is key to the process known as mantle convection, which drives the movement of tectonic plates.

The interactions between the upper mantle and the Earth's crust lead to significant geological activities and phenomena.

Lithosphere

The lithosphere refers to the rigid outer layer of the Earth, ranging from the crust down to the uppermost part of the mantle. This combined layer is divided into large slabs known as tectonic plates.
These plates float on the semi-viscous asthenosphere below and constantly move due to mantle convection currents. The movement can cause earthquakes, volcanic activity, and the creation of mountain ranges.

• The lithosphere is thicker under continents and thinner under oceans.
• It is crucial for understanding the theory of plate tectonics, which explains many geological processes and features.

The lithosphere's dynamics are fundamental in shaping the Earth's surface and influencing environmental conditions.