the branch of geophysics concerned with the magnetism in rocks that was induced by the earth's magnetic field at the time of their formation. Paleomagnetism (or palaeomagnetism in the United Kingdom) is the study of the record of the Earth's magnetic field in rocks, sediment, or archaeological materials. Certain minerals in rocks lock-in a record of the direction and intensity of the magnetic field when they form. This record provides information on the past behavior of Earth's magnetic field and the past location of tectonic plates.
I guess the answer to the blank will be: During the second Red Scare public and government suspicious of Communism led to the blacklisting of people in various industries.
