This photo pair shows what is known as "Marmot Rock" or "Savage Rock" near where the park road crosses the Savage River. The earlier photo shows the first Savage River bridge, completed in 1925. In the later two photos, the bridge is not visible, as it was rebuilt in 1983 south of its previous location. Thus the current bridge is off the right edge of the frame. When comparing the first two photos, note the general increase in shrubs on the high slopes of the mountain. The forest visible in the upper left of the frame has also thickened considerably between the time these two photos were taken. A small stand of balsam poplars has also sprung up just to the right of the rock. When comparing the second two photos, which only span 9 years, can you still see changes that have occurred? Is that patch of forest getting thicker still? What does this tell you about the rate of change occurring?