The Eatrh

The Earth’s crust is a relatively shallow layer. This rocky surface layer is classified into two main types: the continental crust and the oceanic crust. The oceanic crust is about 7 kilometers thick. In contrast, the continental crust has an average thickness of 35–40 kilometers, but in some mountainous regions, it may exceed 70 kilometers. Unlike the oceanic crust, which is composed of chemically uniform materials, the continental crust contains a variety of rock types.

However, the largest volume of the Earth (over 82%) lies in the mantle—a solid, rocky layer extending to a depth of 2,900 kilometers. The boundary between the crust and the mantle shows very distinct chemical differences.

The core is believed to be primarily composed of an iron–nickel alloy with small amounts of oxygen, silicon, and sulfur. Due to the extremely high pressure in the core, its materials have a high density, approximately 14 times that of water at the Earth’s surface.

A characteristic feature of the Earth’s interior is the gradual increase in temperature, pressure, and material density with depth. It is estimated that at a depth of 100 kilometers, the temperature ranges between 1,200 and 1,400 °C, while at the Earth’s center, the temperature may exceed 6,700 °C. The gradual increase in temperature and pressure with depth affects the physical properties and, consequently, the mechanical behavior of the Earth’s materials.

The Earth model with moving plates was built by Engareh Physics Toos Company in 2017 (1396 in the Iranian calendar) at the Earth Physics Park, part of the Earth Science Park Museum in Mashhad.