Often, bergschrunds appear at the head of a cirque. The best way to view it is a hike to Chasm Lake. As glaciers grow, the ridges above them shrink. Eventually, a thin ridge will separate two glaciers. As the glaciers cut closer to each other, they tend to carve out the induvidual sides of a peak, forming a Horn.
Horns are very steep and pointed peaks.
The most famous horn in the world is the Matterhorn. A good Park example of a horn is Pagoda Mountain, southwest of Longs Peak. When a glacier melts, it will occasionally leave small blocks of ice half-buried in the ground. Sheep Lakes in Moraine Park are a good example of kettle lakes, and are very visible from Rainbow Curve on Trail Ridge Road. As more and more rocks are dropped, long ridges form.