United States Meteorite Impact Craters

Astronomical Unit (AU) -

AU - see astronomical unit -

Breccia -

Central Uplift -

Diaplectic Glass -

Excavation -

Ga (Giga-annum) - 1 billion years (usually 1 billion years ago)

GPa (Gigapascals) - 1 GPa is a measure of force per unit area.  1 GPa is equal to roughly 145,000 lbs/square inch or about 10,000 kg/square cm.  This is about 10,000 times normal atmospheric pressure at sea level, about 100 times the pressure exerted by a 100lb woman stepping on your foot with stilleto heels (at the moment of impact), or about 10 times the pressure found at the deepest point in earth's oceans.  (These conversions are very approximate.)

Impact Crater -

Impact Melt -

Impact Structure -

Impactor -

Joules -

ka (kilo-annum) - 1 thousand years

Kilotons -

Kinetic Energy -

K/T Boundary (Cretaceous-Tertiary boundary) -

Ma (Mega-annum) - 1 million years (usually 1 million years ago).

Megatons -

Modification -

Shock-Metamorphism -

Shock-Waves -

Simple Crater -

Strain Rate (geology) -

Yield Strength (geology) -