At the valley heads, glaciers carved mountains into rugged knife edged ridges called aretes, steep solitary peaks called horns and deep depressions known as cirques. A glimpse into the Pickets and up onto T-bone ridge shows all these elements from Newhalem. Glaciers, moving rivers of perennial ice and their associated formations characterize the mountain range. Glaciers sculpt the mountains and influence the activity of rivers . Today, the almost 700 alpine glaciers in the northern Cascade Range are but a fraction of the size of their ice age counterparts, yet account for most of the glaciers in the lower 48 states.
Glacial concentrations surround all major peaks.
Mt. Baker's slopes support 13 glaciers. Glaciers are sensitive to changes in temperature and snowfall. Their constant changes are important climatic indicators. They influence vegetation patterns and serve as reservoirs for domestic and hydroelectric water supplies. In response to cooler summer temperatures and heavier winter snow fall, they have advanced into the head of river valleys several times over the last 800 years.