Chronological dating methods

For example, isotopes with very long half lives are no good for dating rocks younger than about 100 million years.

This is because, in just 100,000,000 years of time, not enough parent will have decayed for daughter concentrations to be reliably measured.

Different isotopes of an element have similar chemical properties (undergo similar chemical reactions) but have different physical properties (such as evaporation rates).

However, we can predict what fraction of the parent atoms will decay over a certain amount of time because each radioactive isotope has a constant rate of decay (unaffected by temperature, pressure, or chemical state).

Mountains, erosion, and variations in climate were considered to be punishment for the sins committed by humanity.

Buffon's Iron Sphere Experiments- On the basis of iron sphere cooling experiments, Frenchman Georges de Buffon estimated that the Earth would have needed 75,000 years to cool to its present temperature.

Carbon-14 has a relatively short half life of 5,730 years. Beyond 60,000 - 80,000 years, there is too little Carbon-14 left in the sample and this technique cannot be used.

Local relationships on a single outcrop or archaeological site can often be interpreted to deduce the sequence in which the materials were assembled.

Sedimentary rocks- Sedimentary rocks are generally not datable using isotopic methods because the grains in sedimentary rocks may come from many different rocks of different ages.

Isotopic age dating would not give the age of the sediment deposition or lithification, but rather the age of the source rocks.

Lyell's extreme form of uniformitarianism would have required a perfect balance between heat production and heat loss.

Kelvin argued that this was physically impossible (the concept is akin to a perpetual motion machine).

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Dating, in geology, determining a chronology or calendar of events in the history of Earth, using to a large degree the evidence of organic evolution in the sedimentary rocks accumulated through geologic time in marine and continental environments.

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