Another prominent K-T extinction theory is that a massive volcanic eruption occurred at this time.
Extensive volcanism could account for the iridium layer. Evidence supporting this theory is found in the extensive volcanic deposits of the Deccan Traps of India and Pakistan, dated at the K-T boundary (West, 1997).
These lava flows would have produced enormous amounts of ash, and gaseous elements which would alter gobal climatic conditions, and change ocean chemistry, possibly causing a mass extinction.
Some speculate that such a massive volcanic event would not have been as explosive, sudden, or global enough to have caused an extinction as extensive as the K-T extinction.
Shocked quartz is not found at volcanic eruptions, even violently explosive ones, and is considered an unequivocal indicator of a meteorite impact (Lemon, 1993).
Regardless of the cause 65mya, the effect was catastrophic!