Earth History: Relative Time and Absolute Time
Geology 1203 Earth history
Assignment: relative time
Preamble:
Understanding Earth history involves determining the sequence of geologic events which occurred over immense spans of time. The geological time scale that we use today was first developed in the
1800’s and is constantly being revised as our understanding improves. Geologists deal with time in two different ways:
Relative Time - the occurrence of events is determined relative to one another (from oldest to most recent). This can be a local series of events or be applied to global events. The eras and periods of the geological time column were established using relative time (mostly based upon the fossil content). Absolute Time - The discovery of radiometric dating allowed geologists to assign a numerical age to the formation of certain rocks. Fixing how old they actually were in billions (Ga), millions (Ma) or thousands (Ka) of years before the present. Hence the term “absolute” time.
These two ways of looking at time are not unique to geologists. You use them everyday. If you agree to meet a friend “after class” - that is a relative time. The time of day when you actually meet is dependent upon when your class is scheduled and when it is finished. If instead you arrange to meet at 1:00pm -that is absolute time.
Part A: Creating A Personal Time Column
In this exercise you are going to create a time column of your own. Begin by creating a relative time column with key events. Then you will assign years to these events fixing them in absolute time. To give you an idea how to proceed I have provided a template with the starting and ending events you should use. Remember that when ordering events you must start with the oldest on the bottom
(when listing vertical) or on the left (when listing horizontally).
Example:
You should start with your birth and end with you taking this course. You may include whatever events you wish in between but you must have at least ten more events.
Assignment: relative time
Preamble:
Understanding Earth history involves determining the sequence of geologic events which occurred over immense spans of time. The geological time scale that we use today was first developed in the
1800’s and is constantly being revised as our understanding improves. Geologists deal with time in two different ways:
Relative Time - the occurrence of events is determined relative to one another (from oldest to most recent). This can be a local series of events or be applied to global events. The eras and periods of the geological time column were established using relative time (mostly based upon the fossil content). Absolute Time - The discovery of radiometric dating allowed geologists to assign a numerical age to the formation of certain rocks. Fixing how old they actually were in billions (Ga), millions (Ma) or thousands (Ka) of years before the present. Hence the term “absolute” time.
These two ways of looking at time are not unique to geologists. You use them everyday. If you agree to meet a friend “after class” - that is a relative time. The time of day when you actually meet is dependent upon when your class is scheduled and when it is finished. If instead you arrange to meet at 1:00pm -that is absolute time.
Part A: Creating A Personal Time Column
In this exercise you are going to create a time column of your own. Begin by creating a relative time column with key events. Then you will assign years to these events fixing them in absolute time. To give you an idea how to proceed I have provided a template with the starting and ending events you should use. Remember that when ordering events you must start with the oldest on the bottom
(when listing vertical) or on the left (when listing horizontally).
Example:
You should start with your birth and end with you taking this course. You may include whatever events you wish in between but you must have at least ten more events.