Images

September 19, 2010: Colorado River, Grand Canyon, River Mile 61.4, Little Colorado River, Across Canyon View from River Right. The gravel bars have changed little in their overall location, lower water levels have allowed riparian vegetation to become established on them. The riparian vegetation, mostly tamarisk and arrowweed, has increased in height and density.

September 19, 2010: Colorado River, Grand Canyon, River Mile 61.4, Little Colorado River, Downstream View from River Right. The muddy water of the Little Colorado River can be seen intermixing with the flow of the mainstem Colorado River, which generally runs clear in Marble Canyon due to the sediment-settling that occurs upstream in Lake Powell.

September 19, 2010: Colorado River, Grand Canyon, River Mile 61.4, Little Colorado River, Downstream View from River Right. The muddy water of the Little Colorado River can be seen intermixing with the flow of the mainstem Colorado River, which generally runs clear in Marble Canyon due to the sediment-settling that occurs upstream in Lake Powell.

September 19, 2010: Colorado River, Grand Canyon, River Mile 65.5, Palisades Creek, across canyon view from river left. The rapid has not changed in the intervening two decades, and many of the same mesquite thickets are still present on the debris fan in the foreground.

September 19, 2010: Colorado River, Grand Canyon, River Mile 65.5, Palisades Creek, across canyon view from river left. The rapid has not changed in the intervening two decades, and many of the same mesquite thickets are still present on the debris fan in the foreground.

September 18, 2010. Colorado River, Grand Canyon, River Mile 52.8, Nankoweap, Downstream View from River Right. Riparian vegetation continues to increase along the river, reducing the amount of sand that is visible at this distance. There has been a slight increase in the amount of mesquite, but overall it appears to be similar to that present 19 years before.

September 18, 2010. Colorado River, Grand Canyon, River Mile 52.8, Nankoweap, Downstream View from River Right. Riparian vegetation continues to increase along the river, reducing the amount of sand that is visible at this distance. There has been a slight increase in the amount of mesquite, but overall it appears to be similar to that present 19 years before.

September 18, 2010: Colorado River, Grand Canyon, River Mile 52.8, Nankoweap Creek, Downstream View from River Right. Sandbars continue to decrease in exposed area owing to erosion and establishment of vegetation, both native mesquite and non-native tamarisk.

September 18, 2010: Colorado River, Grand Canyon, River Mile 52.8, Nankoweap Creek, Downstream View from River Right. Sandbars continue to decrease in exposed area owing to erosion and establishment of vegetation, both native mesquite and non-native tamarisk.

Aerial view of the study area in Canyonlands National Park.

Repeat photograph of Saguaro National Monument (now Saguaro National Park) East, Rincon Mountain District. This photo was taken in 2010 by Dr. Ray Turner, USGS and is a match of a 1935 photograph taken by the National Park Service (NPS).

Repeat photograph of Saguaro National Monument (now Saguaro National Park) East, Rincon Mountain District. This photo was taken in 2010 by Dr. Ray Turner, USGS and is a match of a 1935 photograph taken by the National Park Service (NPS).

Saguaro National Monument is now Saguaro National Park. The decline is saguaros has continued but at a rate slightly less steep than predicted. Very few of the saguaro present in 1935 remain. Meanwhile, the regeneration of this forest has already begun, as shown by findings from a long-term study-plot located at left midground.

A Tegeticula maculata Yucca moth is perched & depositing a pollen ball onto a stigma of a Yucca plant (Hesperoyucca whipplei). Photo by Sherwin Carlquist, 2010.

Beaches in the rough terrain of Grand Canyon are a valued resource by hikers and river runners because they are fairly flat and vegetation free. 

Boats at a large campsite area along the Colorado River in Grand Canyon, 2009. USGS photo, public domain.

Riparian vegetation along West Clear Creek in Arizona. Photo by Chris Calvo, National Park Service. 

Boat equipped with multibeam sonar surveying the bed of the Colorado River in May 2009. Instrument in foreground is robotic total station that automatically tracks boat location and radios the position to a computer on the boat 20 times per second.

Boat equipped with multibeam sonar surveying the bed of the Colorado River in May 2009. Instrument in foreground is robotic total station that automatically tracks boat location and radios the position to a computer on the boat 20 times per second. 

U.S. Geological Survey Research Ecologist Jeff Lovich holding a radioed desert tortoise at the Mesa wind farm near Palm Springs, California.

Repeat photography from about 1945 (top panel) and 2008 (bottom panel) showing channel narrowing over time in a portion of the Rio Grande in Big Bend National Park.