Geography of California

California is a U.S. state on the western coast of North America. It is very big, covering 163,696 square miles (423,970 kilometers squared). The state has many different landscapes. These include the Sierra Nevada mountains, the fertile farmlands of the Central Valley, and the dry Mojave Desert in the south.

California is home to some amazing trees. You can find the tallest trees, like the coast redwood, the biggest trees, like the Giant Sequoia, and some of the oldest trees, like the bristlecone pine. The state also has the highest point, Mount Whitney, and the lowest point, Death Valley, in the 48 contiguous states.

California is generally split into Northern and Southern California. The exact boundary between the two is not always clear. Cities like San Francisco are in Northern California, while Los Angeles is in Southern California. Scientists divide the state into eleven areas, each with its own special features.

State boundaries

California's shape and edges were set a long time ago. Spanish explorers first claimed the land as part of Alta California. In 1819, a treaty named the Adams–Onis Treaty set the northern edge at 42 degrees latitude. Later, after a war between Mexico and the United States, the Treaty of Guadalupe Hidalgo in 1848 set the southern edge. On the east, California’s border has two straight lines. One line runs north to south to the middle of Lake Tahoe. The other angles southeast to meet the Colorado River. From there, the border follows the river to the international border near Yuma, Arizona. These borders were set when California was getting ready to become a state in 1849.

Northern California

Main article: Northern California

Northern California includes the top 48 counties of the state. Big cities here are the San Francisco Bay Area, with places like San Francisco, Oakland, and San Jose, and the state capital, Sacramento. This area has redwood forests, the Sierra Nevada mountains—with Yosemite Valley and Lake Tahoe—Mount Shasta, and the northern part of the fertile Central Valley. The weather changes from cool, foggy coasts to cold, snowy mountains. Besides busy cities, Northern California has quiet spots too. The area is important for technology, clean energy, medicine, government work, and finance.

Klamath Mountains

The Klamath Mountains are in northwest California and southwest Oregon. The highest point is Mount Eddy in Trinity County, California. These mountains have different rocks and soils, which help special plants grow, like Lawson's Cypress and Foxtail Pine. Winters here are cold and snowy, and summers are dry and warm.

Cascade Range

The Cascade Range runs from British Columbia in Canada down to Lassen Peak in California. It is part of the Pacific Ring of Fire, a zone with many volcanoes. Lassen Peak, the last Cascade volcano to erupt in California, did so between 1914 and 1921. This area, near Mount Shasta, is mostly north of the Central Valley and the Sierra Nevada mountains.

Modoc Plateau

In northeast California is the Modoc Plateau, a flat area made from old lava flows. It sits between 4,000 and 5,000 feet above sea level. The plateau has cinder cones, juniper flats, pine forests, and lakes that fill in seasons. Animals like mule deer, elk, and pronghorn live here. Some parts are protected to help wildlife.

Basin and Range

East of the Sierra Nevada is the Basin and Range geological province, which also reaches into Nevada. This area has rows of mountains and valleys formed by Earth's crust stretching. Mono Lake here is one of North America’s oldest lakes. The Owens Valley is one of North America’s deepest valleys. Many dry lake beds in this area hold valuable salt.

Coast Ranges

West of the Central Valley are the Coast Ranges, including the Diablo Range near San Francisco and the Santa Cruz Mountains south of the city. These mountains are home to coast redwoods, the tallest trees on Earth, which grow where coastal fog reaches.

Central Valley

California’s central feature is the Central Valley, a rich valley between the coastal ranges and the Sierra Nevada. The north part is the Sacramento Valley, named after its river, and the south is the San Joaquin Valley, named after its river. Both areas are watered by rivers that flow to the San Francisco Bay. Many cities here, like Stockton and Sacramento, can act as seaports because of these rivers.

Sierra Nevada

The Sierra Nevada mountain range runs north to south for 400 miles along the eastern edge of California. Mount Whitney, the highest peak in the contiguous United States, is here. The Sierra has many sunny days, warm summers, cold winters, and many different landscapes. Famous spots include Yosemite Valley, Lake Tahoe, and huge Giant Sequoia trees. Popular trails such as the John Muir Trail and parts of the Pacific Crest Trail pass through this area, which includes Yosemite National Park, Kings Canyon National Park, and Sequoia National Park.

Southern California

Main articles: Southern California and Geography of southern California

Southern California is the southern part of the state. It has many big cities and open spaces. Over 22 million people live there.

Transverse Ranges

Southern California is separated from the rest of the state by the Transverse Ranges. These mountains stretch from Point Conception to the San Jacinto Mountains in Riverside County.

The Santa Ynez Mountains are the westernmost ranges. Other ranges include the Simi Hills, Santa Monica Mountains, and San Gabriel Mountains. The highest point in these ranges is Mount San Gorgonio.

Mojave Desert

The southeast of California has deserts. These deserts form because mountains block moisture from the ocean. The Mojave Desert is bounded by mountain ranges and extends into Nevada. It receives very little rain each year and has high temperatures.

Peninsular Ranges

The southernmost mountains of California are the Peninsular Ranges, which continue into Baja California in Mexico. These ranges include the Laguna Mountains, San Jacinto Mountains, and others. San Jacinto Peak has a cable tram that takes visitors up the mountain for hiking.

Colorado Desert

East of the peninsular ranges are the Colorado and Sonoran Deserts, which stretch into Arizona and Mexico. The Salton Sea is an inland lake formed when the Colorado River flowed into a dry area in 1905. It is California's largest lake.

Pacific Ocean

The Pacific Ocean lies west of California. The water temperature changes from about 50 °F in the north during winter to around 70 °F in the south during summer. This small change happens because deep waters rise, bringing nutrients for sea life. The waters near California are full of fish, making the sea look green instead of clear blue.

California has a very long coastline, about 840 miles. It is the third longest coastline in the United States after Alaska and Florida.

Geology

Main article: Geology of California

California has many earthquakes because of faults, especially the San Andreas Fault, along the Pacific coast. Some big earthquakes happened in the past. Coastal cities can sometimes be hurt by big waves from undersea earthquakes. California has volcanoes too, like Lassen Peak and Mount Shasta.

Scientists study how Earth's plates move. Long ago, people thought California was an island. In the future, the sea floor might change.

Climate

Main article: Climate of California

California has many different kinds of weather. Near the coast and in the south, it is often warm with rainy winters and dry summers. The ocean helps keep temperatures comfortable.

In winter, coastal storms can bring rain. Eastern parts of the state sometimes have thunderstorms in the summer. Because much of California is dry, wildfires can happen when it is hot and dry. Snow falls in the mountains during winter. Heavy rain or melting snow can sometimes cause flooding. Steep, unstable slopes can lead to landslides during wet weather or earthquakes.