Describe how magnetic reversals help with determining the age of rocks.
Magnetic reversal is a switch between normal polarity (south to north) and reversed polarity (north to south). The north and south magnetic poles have switched many times and this switch in polarity is used to determine the age of rocks. Using isotopically dating sequences of rocks that contain magnetic reversals, magnetic timescale is formed. Direction and strength of the magnetism preserved in rocks is measured with magnetometer. On the timescale there are periods of normal magnetization shown in black and periods of reversed magnetization shown in white. Variability in the spacing and duration of magnetic reversals produced a unique pattern through time and this pattern is used to compare to magnetic timescale to see where the patterns match. This method allows an estimate of the age of the rock or sediment.
The North and South magnetic poles can switch. The geologists created geomagnetic polarity timescale serves as reference to compare against other sequences of rocks.
Scientists measure direction and strength of magnetism in rocks with magnetometer (serves to determine did magnetic field have a normal or reverse polarity).
Cenozoic Era was period of magnetic reversal, for example.
Recommended textbook solutions
More related questions