ENVIRSC 1B03 Lecture 5: Earth Layers Lecture 2.docx

• School: McMaster University
• Department: Environmental Science
• Course: ENVIRSC 1B03
• Professor: Luc Bernier

Document Summary

The inner core is extremely hot and solid. The asthenosphere (upper mantle) is composed of hot magma with some flow. The lithosphere is a thin and brittle crust. The crust forms the upper part of the lithosphere is broke into fragments (plates) Two types of crust: oceanic: dense, thin (7km thick, continental: relatively buoyant (less dense), thick (30 km thick. Movement of the plates is caused by conventional currents with the mantle. Plate boundaries do not tend to match up with the boundaries of continents or oceans. The movement of plates causes dynamic events on earth"s surface, especially at plate boundaries. Types of plate boundaries: divergent (means to spread apart move away ) new land is created at these locations. Results in seafloor is spreading and causes oceanic ridges to form: example: mid-atlantic ridge. The atlantic ocean is getting wider every year: convergent (moving toward each other, oceanic and continental crust.