Nothing in the backcountry gives off heat like a roaring fire. That’s why our recent ancestors built fireplaces in their log cabins — and more remote forebears burned fires in whatever structure they called home.
And since it’s not wise to have a fire in a primitive hut made of sticks and dry vegetation (or a cave, for that matter), it’s good to know of other ways to heat your living and sleeping area. By digging a hot rock heating pit in the dirt floor of a shelter, you can enjoy the heat of a fire – with far less danger to yourself and your shelter. Here’s how.
Start by digging a small pit in the floor of your shelter, a little bigger than the bowling ball-sized rock that you will be using to transfer heat. Dig the hole to match the rock’s size and shape, and find a flat rock to cover the pit. Make sure that you get your two rocks from a dry location (water-logged rocks tend to explode when heated, so do not use rocks pulled from rivers, streams, and ponds). Ensure that everything fits together well before you heat up the stone, since a 1200-degree-F rock isn’t a fun thing to juggle. You could even recess the hole of the pit surrounding the cover, so the flat rock sits flush with the dirt floor (not a trip hazard).
When it’s time to use your set-up, heat up your pit stone in a fire for about an hour (but don’t heat the lid stone). Carry the stone to the pit (a shovel works well), and drop it in. Seal the pit with your flat stone lid, and bask in the radiant heat that will last for several hours.
For sustained heat, you could always have another rock of a similar shape and size to your first rock at the ready, so that when the first rock is done cooling off, the second rock can be swapped in its place to keep the heat going.
This trick works best in very dry soil and with a red-hot rock. Just clear all flammables out of the way as you move the near-molten stone toward the waiting pit!