The amorphous theory, short version, is this: The Earth's interior heats up over time, due primarily to tidal forces, but also perhaps in conjunction with some radioactive decay. Tidal force from the sun/moon, cause the solid inner core to shift constantly within the earth due to the hot fluid mantle between the two.
Imagine a smaller rotating sphere inside a much larger rotating sphere. The smaller sphere rotates faster for every rotation of the larger sphere, since its circumference is much smaller and the friction between the outer surface of the smaller sphere, and the inner surface of the larger sphere, act to mesh the two together. If this wasn't true, the two would rotate at the same speed.
Depending upon the amount of interior heat, viscosity of the molten mass changes and the amount of shifting likely changes as well. This process could build upon itself - compounding the heating.
Eccentric rotational differences, between the solid inner core and the Earth's outer crust, create a kind of pumping action, if you will, which is the real driver behind what is incorrectly called "Convection Currents", IMHO.
Heating of the Earth's interior steadily increases over time until a point is reached where interior heat is released through massive increases in volcanic activity.
Other possible consequences:
The Earth's solid iron core, rotating within the solar plasma/wind given off by our sun, is the source of our magnetic field [IMO].
The magnetic poles may vary because earth's solid inner core poles vary from shifting, as described above. The core may actually flip inside the earth. It may have whole sections that liquefy due to interior heat melting its outer surface.
This may lessen the core's ability to generate a magnetic field; since I don't see how liquid iron would be capable of producing a sustained magnetic field.
Heat buildup could also cause increased tectonic movement; perhaps even slippage of entire plates, like the plot in the movie 2012.
We are witnessing increased volcanic activity, earthquakes, deep earthquakes, sulfuric oxide emissions, increased magnetic pole shifting, a decrease in the strength of the magnetic field, and decreased solar activity.
Ice core samples record increased CO2 emissions around the time of a return to an ice age. Increased CO2 emissions are currently in the news, as the globull warmists keep reminding us.
A direct correlation has been established between lessening solar activity and increased geological activity on earth, albeit from limited available data.
I've seen a number of theories which attempt to explain the correlation, but none seem to fully explain what's behind this phenomenon.
We're only scratching the surface of the complex and cyclic earth/sun interaction. Could the earth's changing magnetic field be the cause of changes in the sun's sunspot activity?
Data demonstrates warm periods, the time between ice ages, what we're in now, last about 12,000 years. The last ice age ended about 12,000 years ago. What do you think is coming next?