Structure of the Earth Structure of the Earth The internal structure of the Earth is layered in spherical shells: an outer silicate solid crust, a highly viscous asthenosphere and mantle, a liquid outer core that is much less viscous than the mantle, and a solid inner core. Scientific understanding of the internal structure of the Earth is based on observations of topography and bathymetry, observations of rock in outcrop, samples brought to the surface from greater depths by volcanoes or volcanic activity, analysis of the seismic waves that pass through the Earth, measurements of the gravitational and magnetic fields of the Earth, and experiments
The Layer Monument Layer Quaternity correspond to the alchemical "deities" of Apollo, Luna, Mercurius and Vulcan as named in "Atalanta Fugiens" (1617) by the German alchemist-physician Michael Maier (Emblem XVII). Collectively the Layer Quaternity are a unique alchemical mandala. Through polarized symbolism they delineate essential coordinates associated with Mandala art, namely Space (Heaven and Earth) and Time (Young and Old). Utilizing variety and multiplicity, key attributes of Northern Mannerist art, they also represent fundamental aspects of the human condition, namely, gender, youth and age, pleasure and suffering. A fifth, uniting symbol, a skull, is located at the very centre of the monument. The