|The one about the snow cave
||[Dec. 7th, 2004|09:15 pm]
Back in the day, every year I'd go snow camping; I did it like 4 years in a row. Two of those years the snow was sufficient to build large snow caves, the other two years we just used tents. I assure you, the snow caves were far warmer.
There are two ways to to build a snow cave; If there isn't a lot of snow, start shoveling a pile together until it is about 6' taller than the surrounding snow, and ~25-30' in diameter, then wait a few hours for the snow to settle. If the snow is deep enough already (over 6') and well compacted, you dig a 6' deep trench, then start hollowing out the sidewall on the leeward side about a foot from the bottom of the trench into a tunnel angled slightly upwards. The tunnel portion of this dig should be about the length of your body, and should rise up a foot or so. Beyond that will be an open trench inside the hollowed out dome portion of the snow cave. Once the tunnel is ~6' long, that should be the starting point for excavation of the dome. Throughout, take the snow you're moving and toss it on top of where the cave will be hollowed out from beneath; after an hour or three (depending on moisture content of snow and coldness of temperature) it will sinter together and help insulate you. Once you have made your tunnel, start excavating above you, the gradually widen out into a dome shape with the "floor" being about two to three feet above the upper tunnel floor. The idea is to have two shelfs about two to three feet above the floor of the tunnel on either side of the trench for people to sleep on. If it is bright outside it will be clear when your excavations have reached close to the surface; the snow will begin to glow a very pale blue from the sunshine outside. Make sure that you keep at least a foot (18" is better - more insulation) of snow on all sides of the dome you are creating above the tunnel (now a trench) and the sleeping floor. You can stick sticks of a premeasured length through the snow from above to determine when you have reached them from the bottom (do this before excavating). The closer you get to the final stopping point, the more care should be taken to ensure uniformity of thickness of wall and such. Smooth over any ridges from shovels on the dome with a gloved hand to help prevent dripping; the nighttime temp will be well above freezing in here. Finally, make a 2" ventilation hole near the top over the trench with a ski pole or other similar instrument. Leave the pole or stick hanging in there should it start snowing and cover up said ventilation hole. Give the pole a shake every now and again to ensure you don't suffocate during the night (the outside temp difference will create a solid wall of ice between you and air, with the exception of the entrance tunnel, which should be well below the grade of where you'll be sleeping. Do not block the entrance tunnel (well, not completely, anyway) so that there will be airflow from the bottom to the top through the vent. You can make a small shelf to light a candle on; this will totally increase the interior temp; just ensure ventilation works by lighting the candle and blowing it out, and observing the residual smoke behavior. (best done while still daylight)
A note on safety; in granular snow conditions do not attempt a cave. The likelihood of collapse is far greater. Always work in teams; one person excavating inside, another helping move the snow from the entrance to the top & sides. Never have both people inside the cave until it is completed and has been freestanding (so to speak) for an hour or so. The outside person must be ready to rescue the inside person should a collapse occur; the conditions for the person inside are identical to those of an avalanche, and that person may only have minutes to live due to suffocation. It is uncommon for a snow cave to collapse after construction, especially after the temperatures drop at night. The cold temperatures tend to increase the overall strength of the shelter. Be aware of the weather, however. If a rainstorm comes through, it'll melt through that foot of snow in no time, and then you'll be feeling blue. And wet.
A note on settling: the ceiling of a snow cave can drop as much as 1-2 inches per day. This occurs because of normal settling of the snow pack. During a heavy storm the settling can increase drastically. When this occurs just reshape the inside of the cave. (this is why you kept the walls nice and thick, right?) Always keep your shovel or digging device next to you in a snow cave. After a storm you may need to dig your way out.
A note on clothing: stay warm by not getting wet, either though melted snow or sweat. A waterproof outfit may be a good idea during excavation, since snow will be coming down all around you, but take it off once the major work is done. Always camp with a partner, and trade off work so one person isn't always hot and sweaty. Regulate your body temperature by eating regularly and modifying the number of layers you are wearing. Continuously drink fluids; it is easier to become dehydrated in the wintertime than the summer in my experience. Your urine shouldn't have hardly any yellow to it; the clearer, the better.
A note on timing: two people should be able to build a shelter such as this (even if one is inexperienced) in no more than four hours. If you do not have that much time until nightfall, other shelters can be made in less time which would be nearly as functional.
In an emergency, snow caves can be created quickly by digging into a snow bank or drift. Eliminate the tunnel and dig a compartment so that it is large enough inside for you & your friend to sit upright. Place your pack in front of the entrance hole. Use evergreen bows or other natural materials to insulate yourself from the ground. Use your pack as an emergency bivy sack and light at least one candle. If you use a candle make sure you have a vent hole or adequate ventilation. If you think people will be out searching for you, make the site as visible as possible from the ground and the air by placing clothing, sticks or stomping an unusual pattern in the snow. Remember when you are inside the cave your ability to hear what is happening outside will be reduced to almost nothing.