Part Two II › Division I I › Section 212 212

The Earth’s Physical Properties

Subject Outline

AThe Earth's gravitational field [see also 131.B.]
- 1Characteristics of the terrestrial field
- 2Measurement of gravitational acceleration [see also 723.D.2.d.]
- 3Interpretation of gravity data: inferences about the Earth's interior
  - aIsostasy: the approximate balance between the elevation of the Earth's surface and the density of the rocks below
  - bGravity anomalies
BThe Earth's magnetic field
- 1Measurement and representation of magnetic fields
- 2Sources and characteristics of the Earth's main magnetic field
- 3Variations in the main magnetic field, including polarity reversals, magnetic storms, magnetospheric substorms, and magnetic pulsations
CThe Earth's electrical properties [see also 127.B.]
- 1Currents produced by the motion of charged particles in the Earth's ionosphere [see also 221.A.3.b]
- 2Electrical conductivity and dielectric behaviour of the Earth's rocks and minerals
- 3Currents induced by magnetic-field variations, currents generated by the Earth's core
DThe Earth's thermal properties [see also 124.A.4.C.]
- 1Sources of the Earth's heat [see also 112.C.5.]
- 2Transmission of heat from the Earth's interior to its surface: thermal conductivity and gradients, heat flow data
- 3Geologic aspects of heat flow: convection currents within the Earth, rock metamorphism, and mountain building
- 4Surface manifestations of heat flow: volcanoes, hot springs, geysers, and related phenomena
EThe mechanical properties of the Earth
- 1The fundamental mechanical properties of the Earth's body and the indirect evidence used to determine them
- 2Nature of deformable media: stress and strain, models of the stress-strain behaviour of materials, seismic waves [see also 126.D.]
- 3The basic internal mechanical properties of the Earth
- 4The Earth's departures from spherical symmetry: oblateness, lateral variations associated with crustal structure, isostasy and its effects [see also 211.A.2.b.]
- 5Anelasticity in the Earth
- 6Response of the Earth to stresses of long duration
FPhysical properties of Earth materials
- 1Volumetric properties: rock density and porosity
- 2Mechanical properties [see also 126.D., E., and G.]
- 3Thermal properties: specific heat and thermal conductivity, thermal expansion and rock melting
- 4Magnetic and electrical properties [see also C.2., above]
- 5Hydraulic properties: porosity and permeability, the capacity to store and transmit fluids
- 6Optical properties: colour, lustre
GThe deformation of materials in the Earth's crust
- 1Stress and strain of rocks
  - aResponse to stress
  - bElastic and plastic deformation
- 2Folding of rocks
  - aTectonic folding
  - bFoliation, lineation
  - cNappes (large rock sheets thrust over other rock formations)
  - dSalt domes and other diapiric structures [see also 724.B.1.b.]
  - eNontectonic folding; e.g., slumping of recently deposited sediments
- 3Fracture in rocks: joints, faults
- 4Structural interference: the superposition of strains produced by the tectonic events of different ages