Mount Rainier Summit Crater

The summit crater of Rainier as see by someone approaching via the Emmons/Winthrop route (Camp Schurman side). The trail leading across the summit crater is the final approach to Columbia Crest (the summit) taken by those who climbed The Mountain via the Disappointment Cleaver route (Camp Muir side). In the foreground is "Register Rock" where the Climbers summit register book is located. Here are a few more interesting facts about the summit: From Geology of Mount Rainier a National Park fact sheet: The volcanic heat has melted a network of ice caves and a small lake underneath the icy summit crater. From Volcano Hazards a USGS fact sheet: The summit itself is formed of two small overlapping craters, each about a quarter mile in diameter; the younger of these forms a nearly perfect circle of radially-outward-sloping lavas. The shallow floors of these carters are filled with snow and ice, but the raised rims are snow-free year-round because of high winds and because much of the ground is still hot. Steam or warm mist, at or just below boiling temperature, rises, from the crater rims in many areas and has melted an intricate system of caves into the base of the crater-filling ice. On calm days, a faint odor of sulfur can also be smelled, as well as the little-eroded shape of the summit craters attest to Rainier’s recent activity.