Geology Reference
In-Depth Information
Radiogenic methods
Fission-track
d
2,000-10,000,000
+
Accumulation of damage trails
(fission tracks) from natural
fission decay of trace
uranium-238 in zircon, apatite,
or glass
Cultural materials, igneous
rocks
Luminescence
100-300,000
Accumulation of electrons in crystal
lattice defects of silicate minerals
resulting from natural radiation
Aeolian deposits, fluvial
deposits, marine
chemical and clastic
deposits, cultural
materials, silicic igneous
rocks
Electron-spin
resonance
1,000-1,000,000
Accumulation of electrical charges
in crystal lattice defects in
silicate minerals resulting from
natural radiation
Cultural materials,
terrestrial and marine
fossils, igneous rocks
Chemical and biological methods
Amino-acid
racemization
500-1,000,000
Racemization of
L
-amino acids to
D
-amino acids in fossil organic
material
Terrestrial and marine plant and
animal remains
Obsidian
hydration
100-1,000,000
Increase in thickness of hydration
rind on obsidian surface
Cultural materials, fluvial gravels,
glacial deposits, clastic
deposits in lakes and seas,
silicic igneous and pyroclastic
rocks
Lichenometry
a
100-10,000
Growth of lichens on freshly
exposed rock surfaces
Exposed landforms supporting
lichens
Geomorphic methods
Soil-profile
development
8,000-200,000
Systematic changes in soil
properties owing to weathering
and pedogenic processes
Soils and most landforms
Rock and mineral
weathering
0-300,000
Systematic alteration of rocks and
minerals owing to exposure to
weathering agents
Landforms
Scarp
morphology
a
2,000-20,000
Progressive change in scarp profile
(from steep and angular to gentle
and rounded) resulting from
surface processes
Fault scarp and other landforms
with scarp-like features (e.g.
terraces)
Correlation methods
Palaeomagnetism
Secular variation
0-10,000
Secular variation of the Earth's
magnetic field recorded in
magnetic minerals
Suitable cultural materials,
sediments and rocks
Reversal
stratigraphy
800,000-10,000,000
+
Reversals of the Earth's magnetic
field recorded in magnetic
minerals
Suitable sediments and igneous
rocks
Continued
