Maybe the only folks to survive were the ones coincidentally sleeping in caves that night - and a piece of Australia.
Is this the same time period as petrified wood?
My understanding is that the population crashes because man was still primarily a hunter gatherer at this stage and because there wasn’t a lot of humanity to begin with. Hunter gatherers are more sensitive to climatic disruptions than farmers (who can deliberately raise/grow and store surplus food for lean seasons and years). As for surviving, those who were far away and under cover were going to have the best chance of surviving the beginning stages of the event. However, the subsequent severe climate disruption led to the death of the plant and animal food sources that the human population depended on and was probably the cause of most of the deaths.
Petrified wood arises from particular circumstances at the time of the plant’s death: large logs are quickly buried in an oxygen-deprived strata where the organic material subsequently fossilizes into stone (by water filtering through the burial and replacing organic materials with minerals). As far as I know, it is not limited to any particular geologic period of the past. As the link below relates, it has even been created in the lab.
http://en.wikipedia.org/wiki/Petrified_wood