Seeps and springs are both places where groundwater emerges from Earth. When seeps and springs emerge from the walls of Grand Canyon, the water contributes to canyon widening by slowly developing and eroding side canyons.

Just as the majority of river downcutting occurs during flooding, canyon widening picks up when dry washes and spring-fed streams flood after heavy rainstorms or considerable spring snowmelts.

The water from a seep, as indicated by its name, flows very slowly to the surface. Water from a spring may flow more readily, creating pools and streams.

Most tributaries in Grand Canyon are sourced by springs, including Bright Angel Creek, which flows through Phantom Ranch (fed by Roaring Springs).

For more information about the Grand Canyon's geology, check out this presentation by the National Park Service.