Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

What is the outermost layer of the Earth called?

1. Crust

2. Mantle

3. Core

4. Atmosphere

The correct answer is: Crust

The outermost layer of the Earth is called the crust, and this is a fundamental concept in geology and Earth science. The crust is the thin, solid outer shell of the planet, and it is where we live. It consists of various types of rocks and minerals, and it can vary in thickness, being relatively thin under the ocean (oceanic crust) and thicker under continents (continental crust). It plays a crucial role in various geological processes, such as plate tectonics, which is responsible for earthquakes, volcanic activity, and the formation of mountains. The crust is directly exposed to the atmosphere and is crucial for supporting life, as it provides the soil and surface environment necessary for ecosystems. In contrast, the mantle is the layer beneath the crust and is much thicker, composed mainly of semi-solid rock that can flow slowly over geological time. The core, located at the center of the Earth, is mainly made of iron and nickel and is divided into a solid inner core and a liquid outer core. The atmosphere is not a layer of the Earth itself but rather a mixture of gases surrounding the planet, which is essential for life and climate. Understanding the composition and structure of these layers is vital for comprehending Earth's geology and the processes that shape it