55 Impact Craters-Mid

Impact Craters FOCUS Question How do impact craters form on Earth's surface?

What Is a Crater A crater is a round dent in Earth's surface. Craters can be as small as a truck tire. Most are bigger. The largest known crater is in South Africa. It is the size of Maine!

What Causes Craters? Some craters. form when a volcano erupts Others form when rocks from space hit Earth. These rocks are called meteors. Meteors can crash into Earth so fast and hard that they leave a hole. These holes are called impact craters. Earth has over 180 known impact craters! Word Wise A meteor is also called a shooting star. It looks like a streak of light that flashes across the night sky. Once a meteor lands on Earth we call it a meteorite.

Kinds of Craters There are two kinds of impact craters. A simple crater is shaped like a smooth bowl. It is usually a shallow dent in the ground Complex craters are usually much larger and deeper. They are rough and have bumps and valleys.

Parts of a Crater Craters have three main parts. Each crater has a floor, a wall, and a rim. These parts are easier to see on a simple crater.

A Young Crater Barringer Crater in Arizona is very young for a crater. It formed less than 50,000 years ago. It is also a simple crater. It is 1 kilometer (3/4 mi.) across. Math Moment How much wider is South Africa's Vredefort Crater than Arizona's Barringer Crater?