Over the years, the land of California has changed. There are two causes of change: natural causes and human causes.
The natural forces that shape the continents are still going on. This happens very slowly, so it is hard to see these changes. Large parts of the earth, called tectonic plates, are pressing together in California.
They are what makes the mountains rise, and they cause earthquakes when they slip suddenly.
Erosion is another slow but steady force on the land of California. When water from snow or rain runs over rocks, it wears the rock away. Over millions of years, this forms channels and valleys.
Changes to the land and geography of California also happen because of humans. The Yokuts Indians who lived here for a long time before the settlers arrived hunted, fished, and gathered acorns to eat. They made houses out of reeds and animal skins. Their way of life changed the land only a little.
When the settlers came, they also hunted animals and birds. But with their guns, they could kill many more animals than they could eat. Soon almost all the Elk that lived in the San Joaquin Valley were gone. They were almost extinct. The Grizzly bears that roamed the valley were all killed by the settlers. Grizzly bears are extinct in California now.
Settlers took water out of the rivers and put it into canals and lakes. They could then use the river water for their crops all year long. As a result of this, Tulare Lake, the largest lake in the western United States, dried up. We now have smaller man-made lakes on many rivers, like Lake Kaweah near Three Rivers and Success Lake near Porterville. People built dams to hold the water in these lakes.
In the 1900s, industry and automobiles came to California. Factories make things and automobiles and trucks drive on our roads. They cause air pollution, which is one cause of global warming. When the air warms, there is less snow in the mountains and less water for humans to use. Air pollution also makes people sick.
Our houses are made of cement, glass, plastic, and other things that are not natural. Our houses have a large impact on the land where they are for a long time.