Hapgood looked at all the terracing around Lake Titicaca that was above the snow line and asked "what's all this then?" Either people lived there long, long ago when the mountains weren't as tall (100s of thousands of years ago), or something made the mountains much taller very, very quickly. Either way, it conflicted with popular science then and now.
Everyone knows that Charles Hapgood was a fruitcake. His theory on "Earth Crust Displacement" was not accepted by the true scientists that know exactly what happened in our history.
Never, ever step out of line if you wish to be respected in your 'community'. You have been warned!