Geology is one area of study contained within the broader category of Earth Science. It is the study of the solid earth. Geology includes studying the internal and external forces and processes which shape the surface of the earth. This means examining the earth's composition & layers and the processes (continental drift and plate tectonics) that shape the surface. These same forces and processes can also contribute to natural disasters. We'll take a closer look at each of these now:
Layers by physical properties
The top layer of earth (the one we live on) is the lithosphere - the solid outer layer of the earth. Underneath it, sits the asthenosphere, a plastic-like solid layer that flows below the continents. Beneath that is the mesosphere, another solid layer, which separates the upper layers from the core of the earth. The core is made-up of the inner core (which is solid) and the outer core (which is liquid).
Layers by chemical composition
The thin top layer of the lithosphere is called the crust. The asthenosphere and the lower portion of the lithosphere make up the mantle. Just like the lithosphere sits on the asthenosphere, the crust sits on the mantle. The mantle is the place where convection happens inside the earth, acting as an energy source which drives many of the process of change we see. Below that is the core - comprised mostly of heavy metals like iron and nickel. The core includes both the inner and outer cores.
Continental drift & plate tectonics
The crust of the earth is made from two different types of crust: continental crust, which makes-up the continents - large landmasses - we see today, and oceanic crust, which sits underneath the oceans. Both types of crust are made-up of sections which move around constantly and fit together like puzzle pieces. These pieces are called Tectonic Plates
Where plates border each other, we see many exciting physical features. When two plates come together or collide (at a convergent plate boundary), these features include large mountain ranges, major earthquakes, and active volcanoes. When two plates move apart or seperate (at a divergent plate boundary), these features include rift valleys, mid-ocean ridges, and slow-forming volcanoes. When two plates slide past each other (at a transform plate boundary) these features include major earthquakes and visible fault lines.
Some good resources for self-study are also available on Geology.com
and at one of the Dynamic Earth Interactive from the Annenberg Learning Center
from or the Smithsonian Museum
Several online courses in geology are also available, including MIT’s OpenCourseWare which offers Introduction to Geology
that introduces the topic and encourages additional readings in the field of geology for highly motivated students.
You might also be interested in joining the The Geological Society of America
To fulfill our tutoring mission of online education, our college homework help and online tutoring centers are standing by 24/7, ready to assist college students who need homework help with all aspects of geology. Our earth science tutors can help with all your projects, large or small, and we challenge you to find better online geology tutoring anywhere.