3. Underlayer. Two-ply long johns and undershirts, (cotton on the inside for comfort, wool on the outside for warmth, are warmer than thermal-knit underwear. Two pairs of socks–a thin pair of cotton socks beneath a heavier wool pair–are warmer and more comfortable than a single thick pair.
4. Midlayer. For warmth and ventilation, wear a tightly woven wool shirt that opens down the front and a quilted jacket over it that also opens in the front. Pants should be of tightly woven wool, cuffless, with plenty of room in the seat and legs, and flaps over the pockets to help keep snow out. For added ventilation use suspenders rather than a belt. A woolen stocking hat or mask-like hat will greatly reduce loss of heat from the head.
5. Outer layer. The main job of the outermost layer is to protect against wind, rain and snow. A parka that covers the hips and has a hood with a full-length zipper is best. If you’re planning on going above the timberline or along windswept ridges, you’ll need a windproof face mask. Down pants, mittens and booties are fine around camp, but are too warm for the trail. Two-piece mittens–a wool liner and a nylon outer shell with a leather palm–are better than gloves.