földkérgi

Földkérgi refers to the Earth's crust, the outermost solid shell of the planet. It is the thin, rocky layer that makes up the surface of the Earth and is where we live. The Earth's crust is composed of various types of rocks, including igneous, sedimentary, and metamorphic rocks. It is divided into two main types: continental crust and oceanic crust. Continental crust is thicker and less dense, forming the continents and their underlying shelves. Oceanic crust is thinner and denser, found beneath the oceans.

The crust is not a uniform layer; it varies in thickness, ranging from about 5 kilometers under the oceans to over 70 kilometers beneath major mountain ranges. This variation is due to geological processes such as plate tectonics, which involves the movement and interaction of large pieces of the Earth's lithosphere. The crust is broken into several large and small tectonic plates that float on the semi-fluid asthenosphere below. Earthquakes and volcanic activity are most common at the boundaries of these plates, where they collide, pull apart, or slide past each other.

The composition of the crust also differs significantly between continental and oceanic regions. Continental crust is primarily composed of lighter silicate rocks like granite, rich in silica and aluminum. Oceanic crust, on the other hand, is predominantly made of denser basaltic rocks, rich in iron and magnesium. The study of the Earth's crust is a fundamental aspect of geology and provides insights into the planet's history, structure, and dynamic processes.