Rocks are piled to make memorials for sherpas and climbers who have died attempting to climb Mount Everest which can be seen shrouded in clouds in the background.

In the moraine of the Khumbu glacier, people have built memorials from glacial rock to those sherpas and climbers who have died trying to reach the summit of Mount Everest. Brightly colored prayer flags, tattered from the extreme conditions, are wrapped around the largest of the memorials. A snow-capped peak can be seen in the background. (Photograph by Ciprian Popoviciu. More about the photograph)

The stacked-stone memorials served as a reminder to Chip and his fellow climbers of the dangers of attempting to summit the world’s tallest mountain, where avalanches are common, falls can spell disaster, and car-sized chunks of falling ice are an everyday occurrence. In addition to the hazards of the terrain, the physical challenges to climbers of Mount Everest are numerous: The high altitude can bring nausea, dizziness, confusion, and death from swelling of the brain. The extreme cold, combined with sustained winds of up to 100 miles per hour, can cause frostbite and hypothermia.

Even the most experienced mountain climbers can perish on the mountain without proper planning, acclimation, and safety procedures. Between 1921 and 2006, 212 deaths were reported on Mount Everest.