Repeat photograph composite, Canyonlands National Park - Salt Creek just upstream from Peekaboo Arch, 1965 and 2015

Repeat photography allows study of ecological change.

The earliest photograph in the composite shows a group of packhorses and several vehicles moving upstream on Salt Creek just upstream from Peekaboo Arch. Taken at the time that Canyonlands was established as a national park, it shows a wide channel with flanking narrow, high floodplains and colluvial terraces resulting from rockfall and eolian distribution under the bedrock walls. Most of the vegetation in the channel is cottonwood with xerophytic shrubs, although a large Gambel oak is present under the shadowed cliff at middle right. Photo: Bates Wilson, 1965, Canyonlands National Park, National Park Service (NPS), stake s6607.

The later photograph shows that channel narrowing and new establishment of cottonwood trees have completely changed the center of this view, which, combined with the clear downcutting effects of recent flooding (note rocks exposure in the channel at center), has erased any trace of the former road. Among the new shrub species present, coyote willow and salt bush are perhaps most common. The cottonwoods and Gambel oak established before 1965 remain alive. Photo: Robert Webb, 2015, USGS, stake s6607.

The USGS and NPS collect and evaluate historic repeat photos for long-term vegetation change.