Mono County, California in the context of "Inyo County"

Yosemite National Park (/joʊˈsɛmɪti/ yoh-SEM-ih-tee) is a national park of the United States in California. It is bordered on the southeast by the Sierra National Forest and on the northwest by Stanislaus National Forest. The park is managed by the National Park Service and covers 1,187 sq mi (3,070 km) in four counties – centered in Tuolumne and Mariposa, extending north and east to Mono and south to Madera. Designated a World Heritage Site in 1984, Yosemite is internationally recognized for its granite cliffs, waterfalls, clear streams, groves of giant sequoia, lakes, mountains, meadows, glaciers, and biological diversity. Almost 95 percent of the park is designated wilderness. Yosemite is one of the largest and least fragmented habitat blocks in the Sierra Nevada mountain range.

Its geology is characterized by granite and remnants of older rock. About 10 million years ago, the Sierra Nevada was uplifted and tilted to form its unique slopes, which increased the steepness of stream and river beds, forming deep, narrow canyons. About one million years ago, glaciers formed at higher elevations. They moved downslope, cutting and sculpting the U-shaped Yosemite Valley.

White Mountain Peak (or simply White Mountain), at 14,252 feet (4,344 m), is the highest peak in the White Mountains of California, the highest peak in Mono County, and the third highest peak in the state after Mount Whitney and Mount Williamson. In spite of its name, the summit block of the peak has large swaths of very dark and colorful orange scree and rock; it is composed of Mesozoic metavolcanic rock, which is igneous rock altered by rising granite.

It is the fourteenth most topographically prominent peak in the contiguous United States. White Mountain Peak is one of only two fourteeners (peaks above 14,000 feet) in California that are not in the Sierra Nevada, the other being Mount Shasta at the far northern end of the state in the Cascade Range. It is the only fourteener in the contiguous United States that is not in the Rocky Mountains, the Cascade Range, or the Sierra Nevada. It is in the Inyo-White Mountains.

The Mono–Inyo Craters are a volcanic chain of craters, domes and lava flows in Mono County, Eastern California. The chain stretches 25 miles (40 km) from the northwest shore of Mono Lake to the south of Mammoth Mountain. The Mono Lake Volcanic Field forms the northernmost part of the chain and consists of two volcanic islands in the lake and one cinder cone volcano on its northwest shore. Most of the Mono Craters, which make up the bulk of the northern part of the Mono–Inyo chain, are phreatic (steam explosion) volcanoes that have since been either plugged or over-topped by rhyolite domes and lava flows. The Inyo volcanic chain form much of the southern part of the chain and consist of phreatic explosion pits, and rhyolitic lava flows and domes. The southernmost part of the chain consists of fumaroles and explosion pits on Mammoth Mountain and a set of cinder cones south of the mountain; the latter are called the Red Cones.

Eruptions along the narrow fissure system under the chain began in the west moat of Long Valley Caldera 400,000 to 60,000 years ago. Mammoth Mountain was formed during this period. Multiple eruptions from 40,000 to 600 years ago created the Mono Craters and eruptions 5,000 to 500 years ago formed the Inyo volcanic chain. Lava flows 5,000 years ago built the Red Cones, and explosion pits on Mammoth Mountain were excavated in the last 1,000 years. Uplift of Paoha Island in Mono Lake about 250 years ago is the most recent activity. These eruptions most likely originated from small magma bodies rather than from a single, large magma chamber like the one that produced the massive Long Valley Caldera eruption 760,000 years ago. During the past 3,000 years, eruptions have occurred every 250 to 700 years. In 1980, a series of earthquakes and uplift within and south of Long Valley Caldera indicated renewed activity in the area.

Inyo County (/ˈɪnjoʊ/ ) is a county in the eastern central part of the U.S. state of California, located between the Sierra Nevada and the state of Nevada. In the 2020 census, the population was 19,016. The county seat is Independence. Inyo County is on the east side of the Sierra Nevada and southeast of Yosemite National Park in Central California. It contains the Owens River Valley; it is flanked to the west by the Sierra Nevada and to the east by the White Mountains and the Inyo Mountains. Mono County is to the north. With an area of 10,192 square miles (26,400 km), Inyo is the second-largest county by area in California, after San Bernardino County which is directly south of Inyo County. Almost half of Inyo County's area is within Death Valley National Park. However, with a population density of 1.8 people per square mile, it also has the second-lowest population density in California, after Alpine County.

Mammoth Mountain is a lava dome complex partially located in the town of Mammoth Lakes, California, in the Inyo National Forest of Madera and Mono counties. It is home to a large ski area primarily on the Mono County side.

Mammoth Mountain was formed in a series of eruptions that ended 57,000 years ago. Mammoth Mountain still produces hazardous volcanic gases that kill trees.

The Bishop Tuff is a welded tuff which formed 764,800 ± 600 years ago as a rhyolitic pyroclastic flow during the approximately six-day eruption that formed the Long Valley Caldera. Large outcrops of the tuff are located in Inyo and Mono Counties, California, United States. Approximately 200 cubic kilometers of ash and tuff erupted outside the caldera.