👉 The term "groundsheet" is a concept in geophysics and engineering related to the properties of the surface layers beneath the Earth's crust. It refers to the layer of rock or sediment that covers the Earth's surface, including the top layer called the lithosphere. The groundsheet can be divided into two main types: the upper lithospheric zone (LZ) and the lower lithospheric zone (LL). The LZ is composed primarily of tectonic plates, while the LL
