If the asteroid had hit the Earth a matter of seconds earlier or later, dinosaurs could well still be doing their dinosaur thing and we would probably not exist.That's the finding of scientists who have been digging around the massive Chicxulub Crater just off the coast of Mexico, which was created when a 15km-wide asteroid hit the Earth about 66 million years ago, an event that is believed to have led to the dinosaur die-off that wiped out giants such as Tyrannosaurus Rex.This is despite the fact that it causes more problems for interpreting rock strata than it solves.And today we know through lab experiments and natural disasters (such as the eruption of Mt. Helens) that major layering of rock strata can happen catastrophically in a short period of time.
by Holli Riebeek • May 6, 2005 Oxygen is one of the most significant keys to deciphering past climates.
The standard scientists use for comparison is based on the ratio of oxygen isotopes in ocean water at a depth of 200-500 meters.
Evaporation and condensation are the two processes that most influence the ratio of heavy oxygen to light oxygen in the oceans.
Another application of radiocarbon dating in the more recent past uses the “bomb curve”.
The figure below depicts the pulse in atmospheric 14C produced from above ground weapons testing that began in the 1950’s, and its decay since the implementation of the Test Ban Treaty in 1963.
The ratio (relative amount) of these two types of oxygen in water changes with the climate.