Question

Which principles help geologists compare the timing of the origin of life forms and the timing of their extinction?

Answer 1

Absolute dating is the process of determining an age on a specified chronology in archaeology and geology. Some scientists prefer the terms chronometric or calendar dating, as use of the word "absolute" implies an unwarranted certainty of accuracy.

Answer 2

Relative dating is the science of determining the relative order of past events (i.e., the age of an object in comparison to another), without necessarily determining their absolute age, (i.e. estimated age). In geology, rock or superficial deposits, fossils and lithologies can be used to correlate one stratigraphic column with another. Prior to the discovery of radiometric dating which provided a means of absolute dating in the early 20th century, archaeologists and geologists used this technique to determine ages of materials. Though relative dating can only determine the sequential order in which a series of events occurred, not when they occur, it remains a useful technique especially in radiometric dating. Relative dating by biostratigraphy is the preferred method in paleontology, and is in some respects more accurate (Stanley, 167–69). The Law of Superposition, which states that older layers will be deeper in a site than more recent layers, was the summary outcome of 'relative dating' as observed in geology from the 17th century to the early 20th century.