Iceberg Lake

As glaciers melt they form rivers of glacial water. From time to time, these streams may bump into the lateral boundaries of larger neighboring glaciers and a dam is formed. A lake begins to form, filling a valley with hundreds of feet of frigid bluish-green water. As the water level rises and the glacier continues to melt, large pieces of ice calve off the face of the larger glacier. Now the lake is brimming with massive icebergs.

  Eventually the lateral boundary, or edge, of the large glacier becomes buoyant with the deepening water. As the edge of the glacier begins lifting, a chasm is opened and the iceberg lake drains. In a very short time (1-3 days) millions upon millions of gallons of water will rush beneath the ice and pour out the toe of the glacier. This is known as Glacial Lake Outburst Flooding (GLOF). We at Alaska Wilderness Trails have the unique privilege of safely traveling in some of these areas (there are times when the water level of the lake is so great the trip must be modified).