Paria Riffle

November 10, 2016

Paria_Riffle

PariaRiver2

Photographer: Patti Weeks
Summary Author: Patti Weeks

The photos above show the Paria Riffle at the confluence of the Paria River and the Colorado River in northern Arizona. The sand and silt-laden Paria River’s reddish-brown color is in distinct contrast to the clear, blue water of the Colorado (upper portion of top photo). Sediments from the once-muddied Colorado River have been deposited in Lake Powell since the 1966 completion of the Glen Canyon Dam 15 mi (24 km) upstream. Tributaries of the Colorado River deposit sand, rocks and even boulders as they enter the main channel, constricting it and causing it to flow faster. The resulting turbulence at these confluences is referred to as a riffle because it's too small to be considered a rapid. Paria Riffle is the first thrill boaters experience on their journey through much rougher rapids in the Grand Canyon.

The Paria River originates near Bryce Canyon National Park in southern Utah. This creek-sized tributary then flows southward through the Grand Staircase-Escalante National Monument in Utah and the Paria Canyon-Vermilion Cliffs Wilderness Area in Utah and Arizona. It joins the Colorado River upstream of the Grand Canyon and slightly downstream of Lees Ferry boat launch site (seen near the upper part of the top photo.)

As shown in the bottom photo, the Paria River’s deposits have contributed to the growth of grasses and shrubs, and have also created a driftwood-lined beach along the tributary’s side of the Colorado. Photos taken on August 20, 2016.

Photo Details: Top - Camera Maker: SONY; Camera Model: DSC-RX100M4; Lens: Sony 24-70mm F1.8-2.8; Focal Length: 25.7mm (35mm equivalent: 70mm); Digital Zoom: 1.938x; Aperture: ƒ/4.5;
Exposure Time: 0.0008 s (1/1250); ISO equiv: 125. Bottom - same except Focal Length: 8.8mm (35mm equivalent: 24mm); Aperture: ƒ/5.6; Exposure Time: 0.0016 s (1/640).