Contrast the usefulness of absolute and relative dating techniques
Two broad categories of classification methods are relative dating and absolute dating.Though using similar methods, these two techniques differ in certain ways that will be discussed in this article.There are many methods employed by these scientists, interested in the old, to get to know the age of items.It is possible to tell the number of years ago a particular rock or archeological site had been formed. Relative dating is qualitative - i.e it can only say one thing is older or younger than another. Relative ages: Relative ages are based mainly on observed or inferred field relationships and stratigraphy/biostratigraphy, rather than laboratory measurements.This means that the oldest are the strata that are lying at the bottom.
However, archeologists still require further information to find out the items that are oldest and those that are youngest in the order.
a metamorphosed igneous rock may give a crystallisation age of 500 million years and a metamorphic age of 400 million years indicating the metamorphism is younger than the igneous rock, which of course this would be self evident from the relative dating observation that the igneous rock was metamorphosed (since the igneous rock could not have been metamorphosed before it formed!
) Both relative and absolute dating can be used to substantiate correlations: e.g.
According to the laws of superposition, a strategic layer that is higher has been deposited more recently.
The oldest strata are at the bottom of the sequence.