Can relative dating always be used
Time in geological terms has been described in two different ways: relative time and absolute time.Relative Time Relative time is the sequence of events without consideration of the amount of time.Source: Tes Teach with Blendspace There are some drawbacks to using relative dating, these include Absolute dating Absolute dating finds the actual age of the object, this would be like you saying you're 15 and your sister is 11.In geology, absolute dating can tell us the approximate age in years of the rock.Fossil remains have been found in rocks of all ages with the simplest of organisms being found in the oldest of rocks. This practice supports the theory of evolution which states that simple life forms gradually evolve over time to form more complex ones.If undisturbed, layers of sedimentary rocks help to determine the relative age of rock: the oldest being at the base and the newest on top.By studying the chemical composition of a rock and knowing the half life of the radioisotopes present we can determine the age of the rock in years.Geological Time | Geologic Time Scale | Plate Tectonics | Radiometric Dating | Deep Time | Geological History of New Zealand | Deep Time Geologic history is often referred to as "deep time," and it's a concept perhaps as difficult to conceive as "deep space".
Stratigraphy is the study of the order of the layers of rocks and where they fit in the geological timescale.
Isotopes have a property know as their The half life of an isotope is the time it takes for half of the atoms to decay, for example the half-life of Uranium is 4.46 billion years!!
This means if you had 10g of uranium it would take 4.46 billion years for 5g of it to decay to lead!
Some isotopes can be very unstable and are likely to break down to form a different atom, in the process they emit radioactivity and are therefore called Radioisotopes. Rocks often contain traces of uranium which is a radioisotope.
It is unstable and eventually decays to form lead, which is stable.