contexts: The interior structure of the Earth is layered in spherical shells : an outer silicate solid crust , a highly viscous 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 with crystalline solids at pressures and temperatures characteristic of the Earth 's deep interior .
name: Structure of the Earth
answers.input_text: short
answers.span_text: an outer silicate solid crust , a highly viscous mantle , a liquid outer core that is much less viscous than the mantle , and a solid inner core
questions.input_text: name the four major layers of the earth in order