Absolute dating supplies a numerical date whilst relative dating places events in time-sequence; both are scientifically useful.This is based upon the spontaneous breakdown or decay of atomic nuclei.The time required for half the original number of parent atoms to decay is called the half life.
The technique gave 90 million years, but took no account of the non-constant erosion rate, or the loss and recycling of salt, or the fact that salt is obtained from other sources as well as continents.
More recently, work has been done on ocean sediments [S. This suggests that, given the current annual rates of erosion (some 27.5 billion tons), all earth's continents would be delivered into the oceans in just 14 million years.
These estimates give 4.4-4.5 billion years for moon rock, and 4.54 billion years for iron metreorites.
These techniques utilize the physical parameters of the earth, such as ice cores, annual lake sediments, and astronomical cycles.
But YE scientists point out some anomalies in relation to C-14 and a very old earth.