Because the exact amount of time this accretion process took is not yet known, and the predictions from different accretion models range from a few million up to about 100 million years, the exact age of Earth is difficult to determine.It is also difficult to determine the exact age of the oldest rocks on Earth, exposed at the surface, as they are aggregates of minerals of possibly different ages.
Free web cam exchange - Radiometric dating assumptions
(According to modern biology, the total evolutionary history from the beginning of life to today has taken place since 3.5 to 3.8 billion years ago, the amount of time which passed since the last universal ancestor of all living organisms as shown by geological dating.) In a lecture in 1869, Darwin's great advocate, Thomas H.
Huxley, attacked Thomson's calculations, suggesting they appeared precise in themselves but were based on faulty assumptions.
However, they assumed that the Sun was only glowing from the heat of its gravitational contraction.
The process of solar nuclear fusion was not yet known to science.
Other naturalists used these hypotheses to construct a history of Earth, though their timelines were inexact as they did not know how long it took to lay down stratigraphic layers.