Hmmm....@Soretna , it's on people like us to revive the much reviled "Crustal Displacement Theory". It really does happen ! The outer skin of our planet isn't quite as RIGID as geologists think it to be .
The outer skin of our planet (Crust) probably does shift due to eccentricity in Earth's orbit around the Sun . It might even get triggered due to occasional (relatively) close "encounters" or "flybys" with the gas giants - Jupiter/Saturn .
This leads to "Polar Shifts" - that's not to say that Pole shifts occur overnight , NO most certainly not ! But a Pole shift could occur over say , a few hundred or more likely , a few thousand years . In geological terms , that's merely the blink of an eye .
What would humans experience at the time a Geographic Pole shift is occuring ?? Well , it would be a period of great turmoil in nature , wherein mega earthquakes would occur frequently , the oceans may slosh around (triggering giant tsunamis) , an ice age getting triggered , massive volcanic eruptions might occur as well . Basically , a BAD time for any civilisation existing during such a phase - almost certainly that civilisation wouldn't survive and mankind would get pushed "back to the stone age" AGAIN - probably a cyclical phenomena that's been repeated a number of times in the story of mankind on Earth :))
The impact on mega fauna would be severe - there is hard evidenc of this . In Northern Canada , Alaska and Norther Siberia , a layer of "MUCK" , about hundred meters thick has been found starting just a few meters underground . This muck consists almost entirely of animal remains , skeletons etc. It implies that mega fauna in their millions had perished whenever Polar shifts occurred .
Regards