Science relative dating
Geology, a major academic discipline, also plays a role in geotechnical engineering.The majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth.More recently, seismologists have been able to create detailed images of wave speeds inside the earth in the same way a doctor images a body in a CT scan.These images have led to a much more detailed view of the interior of the Earth, and have replaced the simplified layered model with a much more dynamic model.This coupling between rigid plates moving on the surface of the Earth and the convecting mantle is called plate tectonics.In this diagram, subducting slabs are in blue and continental margins and a few plate boundaries are in red.They also provided a driving force for crustal deformation, and a new setting for the observations of structural geology.The power of the theory of plate tectonics lies in its ability to combine all of these observations into a single theory of how the lithosphere moves over the convecting mantle.
In practical terms, geology is important for mineral and hydrocarbon exploration and exploitation, evaluating water resources, understanding of natural hazards, the remediation of environmental problems, and providing insights into past climate change.
To study all three types of rock, geologists evaluate the minerals of which they are composed.
Each mineral has distinct physical properties, and there are many tests to determine each of them.
Early advances in this field showed the existence of a liquid outer core (where shear waves were not able to propagate) and a dense solid inner core.
These advances led to the development of a layered model of the Earth, with a crust and lithosphere on top, the mantle below (separated within itself by seismic discontinuities at 410 and 660 kilometers), and the outer core and inner core below that.
When a rock crystallizes from melt (magma or lava), it is an igneous rock.