Our route was due west from Cody: up the middle fork of Granite Canyon, along the Teton Crest Trail, then over Housetop Mountain and the Idaho state line to the Mud Lake trailhead. The track was 20 miles south of the pass John Colter crossed in the winter of 1808, when he became the first explorer to discover what is now Yellowstone National Park. (All he had weresnowshoes, a single blanket, a Winchester and a small bag of supplies.) Before that, the range was the domain of the Blackfeet Indians and before them, the wizened tram operator whispered in a creepy tone, a culture so ancient even archaeologists don’t know what to call it.

On the backside of Cody, we traversed a wide-open bowl and skied fluffy, knee-deep powder to a stand of white-bark pine. Seeing a slot through the trees, I continued past the group and, in true ski-bum style, poached first tracks down a 20-foot-wide powder-choked draw.

One by one, my crew shot out of the forest onto a wide snow-covered meadow at the bottom. There, we clicked our bindings into touring mode and attached the climbing skins (essentially morphing our boards into long, skinny snowshoes) and continued in single file toward the Teton Crest Trail. The big secret about modern alpine touring gear is that it makes going up almost as much fun as going down. Boulders, ditches, deadfall and streams are covered by 40 feet of snow. Everything is smooth and flat, and every step you get a few extra inches of glide  up  as the ski slides to a stop.

We made good time across the mouth of Granite Canyon and were on the first berm 45 minutes after we started. Tall stacks of cumulonimbus clouds passed before the sun and drew sharp shadow lines beneath the trees. Two and a half hours after stepping onto the tram, we entered a clearing where the first igloo was supposed to be.

We had put great faith in the legendary strength of the igloo. Its catenary arch is the same used in the dome of St. Paul’s Cathedral in London and was the inspiration for the Gateway Arch in St. Louis. In the Arctic tundra, the Central Inuit had built igloos for thousands of years that withstood months of wind and weather. Apparently, it takes practice to get it right. The weight of the new snow had crushed the roof of ours in just a few days.

We’d come prepared, though, with our ace in the hole: an igloo-making kit by Grand Shelters called the Icebox. In the DVD that came with the kit, the designer Igloo Ed  a giant, hairy man who could easily be mistaken for Jerry Garcia  says an igloo takes one to four hours to complete.

In reality, it took that long to read the 21-page manual and twice as long to actually build one. After two hours, we had the foundation and three vertical feet of the circular wall finished. The Icebox uses a rectangular form to mold blocks from snow, and a telescoping aluminum pole to measure the arch. We took turns packing the form and moving the pole for six hours. By the time the sun had dipped behind the trees (and the temperature had dropped to 20 degrees), we had set the last block in the roof.