Movement of Lithospheric Plates

The **lithosphere** is the rigid outer cap of Earth. It consists of the Earth’s crust and the solid part of the upper mantle. The term is derived from the Ancient Greek word “lithos”, meaning “rocky”, and “spharia”, meaning “a sphere”. The lithosphere is divided into several parts of different shapes and sizes, called **tectonic plates**. Tectonic plates are in a constant motion, moving around the upper part of the Earth’s mantle – **asthenosphere**.

The upper part of tectonic plates is formed by two basic **types of the Earth’s crust**, which differ in its age, thickness, and geological composition: the **continental crust** – an older, thicker, and lighter (less dense] in comparison to the **oceanic crust** that can be found in the seafloor.

This model shows the Earth's tectonic plates of all sizes and meanings: large, small and so-called microplates. Based on the movements that lithospheric plates perform relative to each other, we distinguish three basic **types of their boundaries: divergent** – the lithospheric plates move away from each other and a new oceanic crust is formed (typical examples are the so-called mid-ocean ridges); **convergent** – the lithospheric plates move towards each other and are destroyed (depending on the type of the lithospheric plate, zonal mountains or ocean trenches are formed); **transforml** – the lithospheric plates move along the so-called transform fault (in the opposite direction or in the same direction, but at different speeds). In the case of transform faults, a new earth's crust does not arise or disappear.

The above-mentioned areas of the boundaries of lithospheric plates represent places where the so-called **endogenous (internal) geological forces of the Earth** are most intensely manifested. Depending on the type of the boundary, there is volcanic, earthquake activity or deformation of the earth's crust and the formation of mountains.

Places with an increased flow of geothermal energy in the asthenosphere are called **hot spots**. They are bound not only to the edges of the lithospheric plates and on the earth's surface show volcanic activity and the formation of chains of volcanic islands (eg the Hawaiian archipelago).

Areas of intense volcanic and earthquake activity on the western, northern, and eastern edges of the Pacific lithospheric plate are referred to as the **Circle of Fire**.