Looking east and a little south from the McDonald summit, the two peaks comprising the prongs of the "horseshoe" are Glacier Peak (9402'—closest), and Mountaineer Peak (9261'). Due to the angle of the shot, and foreshortening, the two summits are not as close together as they appear in this picture, and are in fact not connected by the ridge. The ridge running off to the left of Glacier Peak is known as East Glacier Peak. Careful looking—it helps to click on the image, which will enlarge it—will show a gap between what is considered a third Glacier Peak (the three are shown on maps as "Glacier Peaks"), and Mountaineer Peak.
Photo by Vernon, July 2, 2006.