Was the tilt of the Earth's axis ever larger than 23 1/2 degrees in the past?

This may, indeed, have happened according to some recent research. Although the precise mechanism is not understood, millions of years ago it seems that the polar regions were much warmer than today so that ice deposits were not possible. Apparently this cannot be completely explained by continental drift. If the tilt of the Earth's axix were as high as 54 degrees instead of the current 23.5 degrees, the polar regions would indeed have the required warm climates to explain the fossil data, which means that the equatorial regions would be substantially cooler. The tilt of the Earth is a complex balance of forces in this rotating system. Even the motion of large air masses can change its tilt by measurable amounts even today. With major Ice Ages, it is possible that the vast ice sheets and loss of ocean water could have changed the 'moment of Inertia' of the Earth so that large axial tilts could have been common. One normally thinks that only outside forces can substantially alter a planet's spin and axial tilt, but small internal changes acting over million of years time may also be very effective.

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