|Style over substance|
 The basics
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 led him on 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 speculated 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.
 The real
A phenomenon called true polar wander does in fact exist and has been demonstrated. It is produced when wobbles in the Earth's core, or changes in the topography of the crust-mantle boundary, bringing the two largest of Earth's moments of inertia near equality, with the result of a geographic shift in the locations of the poles. The rotational axis does not shift relative to the stars, but the Earth itself reorients relative to the rotational axis, in the same way that any spinning nonspherical object (say, an egg) will orient its longest axis to its rotational equator.
The rate of this shift is on the order of 1 degree per million years, though a more rapid shift occurred, about 800 million years ago, of 55 degrees over the course of 20 million years (2.75 deg/My). Rapid pole shift of the cataclysmic variety (on a timescale of years or less) would require a titanic change of the Earth's moments of inertia on a similarly outlandish timescale. Barring a massive planetary collision comparable to the hypothesised Earth-Theia collision, mechanisms that could cause such major changes in the inertial moments of a 5.9x1024-kg body with a mean density of 5.515 g/cm3 are somewhat difficult to imagine, and the effects of crust displacement would then be utterly trivial compared to the effects of the forces causing it.
Other Solar System bodies as Mars, Enceladus, and Europa are thought to have also experienced the true polar wander effect, with the latter having almost flipped over.
 Batshit insane
There are many very glaring problems with these ideas, which many cranks seem to ignore when ranting about them.
The first is that as the crust of the planet is a really big shell of solid rock, changing the axis of rotation would take a massive amount of force. Hapgood explained that the area around the outer core would have heated up and caused the crust to rotate freely, which means somehow it would suddenly change direction randomly instead of obeying Newton's first law of motion and continuing to rotate in the same direction. How the interior would have heated up he did not go into.
To give an approximate value on forces, a large body is estimated to have impacted Mars, creating a crater that covers 40% of the surface of the crust: The Borealis Basin. The axis of rotation shifted 25 degrees from vertical, similar to Earth's, and Mars is less than a ninth the mass of Earth. The impact claimed to have caused the Earth's axis to be shifted in relation to the plane of orbit (23 degrees), and to have caused the formation of the Moon, hit so damn hard it is thought the entire crust and a large part of the mantle were pulverized and thrown into orbit before raining back down into a planetary magma ocean. Both seem to have continued to rotate around the same axis as well.
Hapgood explained that one of his proofs was a map that seemed to show a 15 degree of shift in the axis of rotation in 9,600 BCE. If this happened quickly, and Hapgood explains in the hypothesis that it would be very sudden, all things on the crust would have suddenly moved 1,000 miles from where they were located… meaning all the animals would have been wiped out by hitting solid objects at over 1,000 miles/hour. Also the shift would have wiped out all tall geological features, including delicate ones like the arches in Utah.
Of the several hundred maps Hapgood references, only the Piri Reis map seems to be real. For some reason no one else has been able to find any of the other maps, which seems to bring out the conspiracy minded (but who would benefit from this deception is completely unknown). Besides pretty much every other historian disagreeing with his interpretation, Hapgood never thought that maps 11,000 years old might be distorted, out of scale, or even wrong.
 Even worse
Hapgood's Crust Displacement Hypothesis was used for the plot of the awful movie 2012, which was plagued by insane explanations.
The film used neutrinos emitted by the Sun to explain how the interior of the Earth would have heated up, by showing the heat boiling the mile-long column of water in their neutrino detector. How it heated up the water there, and not heating any of the water in the oceans, lakes, rivers, and in the cells of all living beings is unknown. In addition it states they only heated up the outer core, and not doing anything to the thousands of miles or rock between the Sun and the outer core. In the time it took you to read this paragraph, you've already had hundreds of trillions of neutrinos pass through you (50 trillion a second is the average).
While flying the aircraft to China, the crust of the Earth supposedly rotated several thousand miles so they would get there instead of crashing in the ocean. How no human felt this movement, by slamming into solid objects and turning into chunky salsa, while the ocean was moved by it to the point of wiping out Washington, D.C. and crossing the Himalayas in a tidal wave is unknown.
 Later writers
Richard W. Noone predicted this cataclysmic shift would happen in 2000 with his book 5/5/2000, ICE: The Ultimate Disaster.
William Hutton wrote a book in 1996 called Coming Earth Changes: Causes and Consequences of the Approaching Pole Shift, where he predicted it would happen before the end of 2001. Not to be stopped by his abject failure he co-authored a book in 2004 (with Jonathan Eagle) Earth's Catastrophic Past and Future: A Scientific Analysis of Information Channeled by Edgar Cayce where he just said it would happen "soon."
- ↑ The Path of the Pole by Charles H. Hapgood (2015). Adventures Unlimited Press, 2nd ed. ISBN 0932813712.
- ↑ 5/5/2000, ICE: The Ultimate Disaster by Richard W. Noone (1997). Three Rivers Press. ISBN 0609800671.
- ↑ Coming Earth Changes: Causes and Consequences of the Approaching Pole Shift by William Hutton (1996). A.R.E. Press. ISBN 0876043619.
- ↑ Earth's Catastrophic Past and Future: A Scientific Analysis of Information Channeled by Edgar Cayce by William Hutton & Jonathan Eagle (2004). Universal Publishers. ISBN 1581125178.