What layer of the Earth is located directly under the crust?

The layer of the Earth that is located directly under the crust is indeed the upper mantle. The Earth's structure is composed of several layers, starting from the outermost layer, which is the crust, followed by the mantle. The mantle itself is divided into two main sections: the upper mantle and the lower mantle. The upper mantle is characterized by semi-solid rock and extends to a depth of about 660 kilometers below the Earth's surface. It plays a crucial role in tectonic activity, as the movement of the upper mantle influences the motion of tectonic plates.

The core, while a significant part of the Earth's structure, is located much deeper than the crust and the upper mantle. The atmosphere is a layer of gases surrounding the Earth and is not part of its internal structure. The lower mantle sits beneath the upper mantle and is further from the surface, which solidifies the upper mantle's position as the immediate layer beneath the crust. This scientific understanding of the Earth's layers is critical for studying geology and tectonic processes, reinforcing why the upper mantle is the correct answer.