The bleakness is part of the appeal for me... if the weather is stormy it makes the rugged scenery all the more dramatic. No accounting for taste I suppose!
"Prehistoric times" is quite a big window... sometimes it would have been frozen tundra, other times a sub-tropical rainforest depending on where the climate was. The landscape would have been somewhat changeable too.
The railway itself had a slow start... first opened in 17,000 BCE, it didn't really take off until the development of the wheel. Prior to that, cave-passengers were expected to help push the vehicles along on rudimentary skis. The "long drag" was then known as "the really long shove".