Laboratory eight dating of rocks fossils and geologic events
Geologists use a wide variety of methods to understand the Earth's structure and evolution, including field work, rock description, geophysical techniques, chemical analysis, physical experiments, and numerical modelling.
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.
When a rock crystallizes from melt (magma or lava), it is an igneous rock.
This rock can be weathered and eroded, then redeposited and lithified into a sedimentary rock.
Transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes.
Plate tectonics also has provided a mechanism for Alfred Wegener's theory of continental drift, in which the continents move across the surface of the Earth over geologic time.
) is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time.
Geology can also refer to the study of the solid features of any terrestrial planet or natural satellite, (such as Mars or the Moon).
At the later end of the scale, it is marked by the present day (in the Holocene epoch).
Mineralogists have been able to use the pressure and temperature data from the seismic and modelling studies alongside knowledge of the elemental composition of the Earth to reproduce these conditions in experimental settings and measure changes in crystal structure.
These studies explain the chemical changes associated with the major seismic discontinuities in the mantle and show the crystallographic structures expected in the inner core of the Earth.
Geology describes the structure of the Earth beneath its surface, and the processes that have shaped that structure.
It also provides tools to determine the relative and absolute ages of rocks found in a given location, and also to describe the histories of those rocks.
The blue blob in the cutaway section is the seismically imaged Farallon Plate, which is subducting beneath North America.