Charles Hutchins Hapgood (May 17, 1904 – December 21, 1982) was a major
crank proponent of the crust displacement hypothesis. He wrote books such as the The Earth's Shifting Crust (1958), Maps of the Ancient Sea Kings (1966), and The Path of the Pole (1970) to explain it. The theory has also been integrated and changed by several other "theorists" in later times into a larger theory called the cataclysmic pole shift hypothesis in an attempt to sound like the more legitimate scientific theories of true pole shift.
Hapgood was a historian (MA Harvard) who was working on his Ph.D. on the French Revolution when he was forced to drop out when the Great Depression dried up his funding. He served several stints during WW2 in different military intelligence agencies, the Red Cross, and finally a liaison officer between the White House and the Office of the Secretary of the War. He settled down teaching history at the Springfield College in Massachusetts till he was hit by a car and died in 1982.
Hapgood believed that continental drift didn't exist, but wanted to find an explanation for changes in the Earth's features over time that explained historical lost continents instead of the theory of plate tectonics that replaced it (supposedly started by a student's question on the fictional continent of Mu). This lead on him the quest that brought him to numerous archival maps in the Library of Congress that supposedly showed ancient coastlines and a large southern lost continent that became Antarctica. So he theorized that the crust has shifted suddenly in relation to the rotational axis at periods of time in the past, causing massive changes to the crust.
Hapgood was able to get a forward written in his book The Earth's Shifting Crust by Albert Einstein before his death in 1955. This was a period where continental drift was discredited and plate tectonics was validated by the mid-Atlantic ridge.