Photo: Craig John

Everest is composed of three distinct layers of rock:

1) The bottom layer, extending upwards to 24,500ft, consists of a light-colored gneiss, most of which is permanently covered with snow and ice.

2) The middle layer is metamorphosed shale containing granitic intrusions and bands of material like quartzite which formed from sandstone through heating and recrystallization. Easily eroded, this layer contains rugged cliffs and fantastic pinnacles.

3) Layer three begins at 27,500 feet, the first 500 feet of which consists of yellow limestone known as the Yellow Band. This feature actually slices through Everest at an angle and is most pronounced on the North Face. (On the south side, it's visible around 24,000ft.) Above the Yellow Band is more limestone but here the color is dark grey; it can be seen most prominently in the First and Second Steps of the Northeast Ridge.