Relative age dating diagrams
To deal with many of these problems geologists utilize two types of geologic time: relative time and absolute time.Relative time places events or formations in order based on their position within the rock record relative to one another using six principles of relative dating.Relative time can not determine the actual year a material was deposited or how long deposition lasted; it simply tell us which events came first.This process lead to a system of time containing eons, eras, periods, and epochs all determined by their position in the rock record.In geology, when an igneous intrusion cuts across a formation of sedimentary rock, it can be determined that the igneous intrusion is younger than the sedimentary rock.There are a number of different types of intrusions, including stocks, laccoliths, batholiths, sills and dikes.Each chapter will include a few questions designed to test your knowledge of material covered in the chapter and in the Internet-based resources.
Though relative dating can only determine the sequential order in which a series of events occurred, not when they occurred, it remains a useful technique.
Making this processes even more difficult is the fact that due to plate tectonics some rock layers have been uplifted into mountains and eroded while others have subsided to form basins and be buried by younger sediments.
With out individual time stamps the process of dating these structures could become extremely difficult.
This feature is produced by changes in deposition over time.
With this in mind geologist have long known that the deeper a sedimentary rock layer is the older it is, but how old?
The principle of Uniformitarianism states that the geologic processes observed in operation that modify the Earth's crust at present have worked in much the same way over geologic time.