Happy Isles is a group of small isles in the Merced River

Merced River

The Merced River , in the central part of the U.S. state of California, is a -long tributary of the San Joaquin River flowing from the Sierra Nevada into the Central Valley. It is most well known for its swift and steep course through the southern part of Yosemite National Park, and the...

 in Yosemite National Park

Yosemite National Park

Yosemite National Park is a United States National Park spanning eastern portions of Tuolumne, Mariposa and Madera counties in east central California, United States. The park covers an area of and reaches across the western slopes of the Sierra Nevada mountain chain...

, California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, USA

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. They are located at the easternmost end of the Yosemite Valley

Yosemite Valley

Yosemite Valley is a glacial valley in Yosemite National Park in the western Sierra Nevada mountains of California, carved out by the Merced River. The valley is about long and up to a mile deep, surrounded by high granite summits such as Half Dome and El Capitan, and densely forested with pines...

 floor. This scenic spot is the starting point for the Mist Trail

Mist Trail

The Mist Trail is one of the most popular short hikes in Yosemite National Park, California, USA. The hike follows the Merced River, starting at Happy Isles in Yosemite Valley, past Vernal Fall, Emerald Pool, to Nevada Fall.-Description:...

, and is also the northern trailhead for the John Muir Trail

John Muir Trail

The John Muir Trail is a long-distance trail in the Sierra Nevada mountain range of California, running between the northern terminus at Happy Isles in Yosemite Valley and the southern terminus located on the summit of Mount Whitney . For almost all of its length, the trail is in the High Sierra...

.

Happy Isles is located where the slope of the Merced River changes from the much steeper upper main stem to the essentially flat Valley floor. At Happy Isles, the river gradient is approximately 2%. The gradient of the Merced River at Happy Isles is steeper than in the Valley floor, and the channel of the river is cut into erosion

Erosion

Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

-resistant granitic

Granite

Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

 boulders and talus

Scree

Scree, also called talus, is a term given to an accumulation of broken rock fragments at the base of crags, mountain cliffs, or valley shoulders. Landforms associated with these materials are sometimes called scree slopes or talus piles...

 materials, compared to channel deposits of sands and gravel present on the Valley floor. The steeper gradient and composition of streambed materials together impede meander

Meander

A meander in general is a bend in a sinuous watercourse. A meander is formed when the moving water in a stream erodes the outer banks and widens its valley. A stream of any volume may assume a meandering course, alternately eroding sediments from the outside of a bend and depositing them on the...

ing patterns from developing in this area.

The area near Happy Isles sustained damage in 1996 during a rockslide

1996 Yosemite Valley Landslide

The 1996 Yosemite Valley landslide occurred July 10 1996 near the Happy Isles trailhead in Yosemite Valley, Yosemite National Park, Mariposa County, California. 162,000 tons of rocks and other debris fell to the ground at over 160 miles per hour. Of 12 campers/hikers involved in the incident, one...

. A number of signposts near the Isles are dedicated to the rockfall.