ecology5.html

Meteor Impact:

Geologic evidence of a catastrophic extra-terrestrial collision is found within two layers of clay: the Magic Layer (3mm thick), and the Ejecta Layer (2cm thick), which were deposited at the same time that the extinction occurred (Smith, 1997).

These clay layers have been found globally in a variety of environments, both marine and non-marine.

The Magic Layer contains unusually high levels of iridium, found only in the earth's mantle, and in extraterrestrial meteors and comets (Smith, 1997).

Other evidence supporting the chemical signature of an extra-terrestrial impact lies in the presence of the mineral coesite, a high-pressure form of quartz - a.k.a. "shocked quartz".

Quartz is a mineral which does not normally show cleavage (planes of fracture). Under enormously high pressure, quartz can form parallel pseudo-cleavage planes.

Shocked quartz is found around nuclear test sites, and known asteroid impact sites (Smith, 1997).

Further evidence supporting a meteorite impact is in the abundant presence of tektites in the Ejecta layer of clay at the K-T Boundary.

Tektites are formed from the energy of collision at impact zones causing molten rock to be ejected into the air. The molten rock quickly cools to form small glass beads (not crystals). These glass beads are the tektites. Once deposited the glass often devitrifies to form clay minerals (Hildebrand, 1996).

(West, 1997)
The two layers of clay: the Magic Layer (3mm thick), and the Ejecta Layer (2cm thick), which were deposited at the same time that the extinction occurred. The Magic Layer contains unusually high levels of iridium, and there is an abundant presence of tektites in the Ejecta Layer.

(West, 1997)
The presence of shocked quartz - tiny grains of quartz that show features diagnostic of the high pressure of impact - found in the boundary layer provides additional evidence of an extra- terrestrial impact at the Cretaceous-Tertiary boundary layer.

(Hildebrand, 1996)
Unaltered tektite glass separated from the K-T boundary Ejecta Layer as preserved at the Mimbral locality, Tamaulipas state, Mexico. This photograph shows the dark brownish-green glass which is the most commonly preserved material. The yellow and amber grains represent partially hydrated glass, the hydration is apparently the first step towards alteration/replacement.
(Hildebrand, 1996)
Altered tektites produced by the Chicxulub impact as preserved at the Dogie Creek, Wyoming, K-T boundary locality. Originally composed of glass, the tektites have been pseudomorphed (altered and replaced by a secondary mineral while their shape is preserved) by phosphate bearing minerals (most commonly goyazite) at this site.