Happy Isles is a group of small isles in the

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 San Joaquin Valley. It is most well known for its swift and steep course through th ...

Yosemite National Park Yosemite National Park ( ) is an American national park in California, surrounded on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The park is managed by the National Park Service and covers an ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

, USA. They are located at the easternmost end of the

Yosemite Valley Yosemite Valley ( ; ''Yosemite'', Miwok for "killer") is a glacial valley in Yosemite National Park in the western Sierra Nevada mountains of Central California. The valley is about long and deep, surrounded by high granite summits such as Hal ...

floor. This scenic spot is the starting point for the

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

, and is also the northern trailhead for the

John Muir Trail The John Muir Trail (JMT) ( Paiute: Nüümü Poyo, ''N-ue-mue Poh-yo'') is a long-distance trail in the Sierra Nevada mountain range of California, passing through Yosemite, Kings Canyon and Sequoia National Parks. From the northern terminus a ...

. Happy Isles is also the trailhead for popular hiking destinations along the Mist Trail (including

Vernal Falls Vernal Fall is a waterfall on the Merced River just downstream of Nevada Fall in Yosemite National Park, California. Like its upstream neighbor, Vernal Fall is clearly visible at a distance, from Glacier Point, as well as close up, along the Mi ...

and

Nevada Falls Nevada FallThe official spelling is singular, see is a high waterfall on the Merced River in Yosemite National Park, California. It is located below the granite dome, Liberty Cap, at the west end of Little Yosemite Valley. The waterfall is wide ...

) and

Half Dome Half Dome is a granite dome at the eastern end of Yosemite Valley in Yosemite National Park, California. It is a well-known rock formation in the park, named for its distinct shape. One side is a sheer face while the other three sides are smoo ...

. 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 In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p is the "direction and rate of fastest increase". If the gr ...

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 is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dis ...

-resistant

granitic A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz- ...

boulders and talus 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 A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediments of an outer, concave bank ( cut bank) and deposits sediments on an inner, convex ba ...

ing patterns from developing in this area. The area near Happy Isles sustained damage in 1996 during a rockslide. A number of signposts near the Isles are dedicated to the rockfall.

References

External links

USGS: Happy Isles Webcam
Merced River Landforms of Mariposa County, California Landforms of Yosemite National Park River islands of California Uninhabited islands of California {{MariposaCountyCA-geo-stub