chapter+4+summary

Chapter 4 Summary

__Section 1: Earth's Interior__ Scientists use many types of evidence to learn about Earth's interior. Two main ways that they use are evidence from rock samples and evidence from seismic waves. The earth has four layers, the crust, the mantle, the outer core, and the inner core. Each layer is very different in size,temperature, composition, and pressure. The crust is where we live and is the rocky layer that forms along Earth's surface. It is the thinnest layer on Earth. The mantle is the thickest layer and has three main parts; the lower mantle, the lithosphere, and the asthenosphere. The two cores are in the very center of the Earth. Scientists believe that the outer core created Earth's magnetic field. The magnetic field effects the entire Earth. by Amy

__Section 2: Convection In The Mantle__ S 6.4.c. Students know heat from Earth's interior reaches the surface primarily through convection. We learned types of heat transfer: radiation, conduction, and convection. Convection occurs in the mantle, as heat from the core and mantle itself cause convection currents. Cooler denser rock sinks as the warmer less dense rock rises, then cools which creates the cycle. by Mason

__Section 3: Drifting Continents__ Have you ever noticed on a map how South America seems to fit into Africa? Well, you're not the only one. In 1910, a young German scientist named Alfred Wegner hypothesized that the continents had moved. The theory was called continental drift and the landmass that he thought the continents had broken off of was called Pangea. Wegner gathered evidence form land features such as South America fitting into Africa, and the fact that their mountain ranges lined up. Using evidence from fossils, Wegner showed that fossils from a fern like plant called Glossopteris have been found in Africa, South America, Australia, India, and Antarctica. Fossils from Mesosaurus and Lystrosaurus, two water reptiles, have been found in places now seperated by oceans. Even though he made these connections, his theory lacked crucial evidence and was therefore, rejected by other scientists.

By: Zoe Berkowitz