Geoscience Reference
In-Depth Information
convection
transfer of heat by the physical movement of molecules from one place to
another; hot, less-dense fluid rises and cool, denser fluid sinks.
cordillera
mountains of western North America from the Rocky mountains to the Pacific
coast.
core
iron-rich centre of the Earth, 2889-6371 km below the surface.
cosmic rays
atomic muclei, largely protons, travelling at or near relativistic speeds.
craton
(1) large stable part of a continent, which has not been subject to deformation for a
very long time (e.g., since the Precambrian); (2) distinct, tectonically coherent, large region of
granitoid crust.
cumulate
term applied to rocks formed by the accumulation (e.g., by precipitation) of
crystals.
Curie point or temperature
temperature above which a mineral cannot be permanently
magnetized.
declination
horizontal angle between geographic north and magnetic north.
decollement zone
detachment (unsticking) zone between strata, due to deformation such as
folding or thrusting.
dehydration
loss of water.
density
ratio of the mass of a material to its volume; usual symbol,
ρ
.
depleted mantle
mantle that has been depleted of some elements by processes such as partial
melting; residue after extraction of crust.
dextral fault
see
right-lateral fault.
diapir
body of light material (e.g., salt, magma) that pierces upwards into overlying strata.
differentiate
(1) mathematical term; (2) rock formed by magmatic differentiation (e.g.,
precipitation of crystals).
dilatation
change in volume per unit volume.
dip-slip fault
fault on which the movement is parallel to the dip of the fault; thrust fault or
normal fault.
dunite
rock dominantly composed of olivine.
dyke (dike)
small igneous body that has intruded into fissures that cut across the existing
rock strata.
earthquake
sudden violent movement within the crust or upper mantle.
earthquake epicentre
point on the Earth's surface immediately above the earthquake focus.
earthquake focus
location of the earthquake within the Earth.
eclogite
type of dense rock formed by metamorphism of basalt.
elastic limit
maximum stress a body can withstand without being permanently deformed.
