Which will drain less body heat: lying on bare earth or bare rock?

Question

For years I backpacked without a sleeping pad, until one particularly chilly night during which I tried to heat up the earth with my paltry 98.6 degrees F (37°C).

In that instance, would I have been better off sleeping on bare rock, or on bare dry soil? No leaf-litter etc. was available.

Answer 1

From experience I can tell you that lying on rock is the most effective way to become cold over night.

Bare Earth

1. Has at least some air gaps in the soil, which insulate (not too much).
2. If there is any soil, the vegetation and roots provide some insulation.
3. Does not reach as cold a temperature as rock, 24" below the surface is a consistent 40-50 degrees during three seasons.

 

Rock

1. Can change temperature dramatically from day to night. (60+ degrees)
2. Has 0% air gaps for your body to warm up.
3. Has great potential thermal conductivity against your body.

 

Conclusion

If you must sleep on one of these try the following.

• Attempt to find dry or dead grasses. Cut a lot of it up and make a bedding.
• If you cannot find grasses, or to provide more insulation, use extra clothes to make a layer between yourself and the ground.
• Use your empty backpack to provide even more of a buffer between your torso (where all the heat is) and the ground.
• Sleep with a hat on.
• Boil water, pour it into a one litre bottle, cover the bottle with a sock, and store in your sleeping bag between your legs or under your arms.