TThis photo pair shows two technical aerial photographs of the middle reach of the Rock Creek drainage near Denali National Park and Preserve headquarters. The first image is from 1981, the second from 2004. This view shows an elevational cross-section of the landscape from forest in the valley bottom, through treeline, to tundra on the high ridges. There are also extensive areas of tall alder shrub communities on the steep slopes above the creek in the subalpine zone. The forest in this area is primarily white spruce (Picea glauca) but in the right-side of the frame (above Rock Creek) you see areas with much lighter-colored vegetation on the south-facing slopes. These are stands of aspen that were established after a wildfire in 1924, likely started by embers from a coal-fired train in that hot, dry summer. Aspen are an early successional species that frequently follow fire in interior Alaska, particularly on southern exposures and dry landscape positions.