Everybody knows rocks fall under one of 3 classifications-sedimentary, igneous, and metamorphic.  But did you know there are scientist who actually specialize in each one of the 3 varieties? They spend their time studying and exanimating a specific type of rock to gather information on how the Earth was formed, the history of the Earth and to predict the future of the Earth.

You can read about the Sedimentology or the study of sedimentary rocks here:   Sedimentary Rocks

Igneous rocks, such as granite or basalt, are formed through the solidification of molten material (magma or lava). Most of the Earth's oceanic crust is made of igneous rock. Igneous rock basically has two types, extrusive- formed by the cooling of molten magma on the earth's surface.  and intrusive-(the majority of igneous rocks) and are formed by magma that cools and solidifies within the crust of the Earth.

Igneous petrology is the study of igneous rocks, or rocks that are formed from volcanic activity and/or from magma. Igneous petrology is a very important field because it helps us understand the processes that shaped the Earth’s crust, past volcanic activity, and the formation of minerals and rocks. It also has practical applications in fields such as mining and petroleum exploration.

By studying igneous rocks and interpreting the information they contain, we can deduce processes that take place within the earth and we can understand volcanic processes that take place on the earth’s surface. For example, at the end of the Triassic period, 245 million years ago, the greatest mass extinction ever known took place, wiping out more life forms on earth than the mass extinction that led to the demise of dinosaurs 65 million years ago at the end of the Cretaceous. At the end of the Triassic, a huge amount of basalt erupted onto the earth. Many geologists think that the gases and particles released into the atmosphere by those eruptions may have been a major factor in the cause of the Triassic mass extinction. Those scientists are studying the information contained in the basalts of that age to further test their hypotheses.

The textures and structures preserved in igneous rocks provide information about their evolution, emplacement, and crystallization. Thus, igneous petrologists are concerned with the entire spectrum of processes that describe how magmas are produced, how they ascend through the mantle and crust, their mineralogical and geochemical evolution, and their eruption or emplacement to form igneous rocks.

Igneous petrologists depend heavily on their field observations, but since most igneous rock is deep below the earth, they also use experimental petrology to reproduce conditions in a laboratory. Although results may not be absolute proof, the data recovered in these experiments is very important. They also use geochemistry to study igneous rocks. The dating of igneous rocks determines when magma solidified into rock. Radiogenic isotopes are frequently used to determine the age of igneous rocks.

In 1980, the volcano Mount St. Helens erupted, triggering a magnitude 5 earthquake and spewing ash, mud and debris across southwest Washington. The explosion killed 57 people and changed the mountain’s landscape forever. Though there are scientist (volcanologists) who study just volcanic activity. The study of Igneous Petrology may lead to answer on what caused the explosion and could it happen again.

Check back next month to learn about the scientist who study the third classification of rocks, Metamorphic Rocks.

Happy Hunting!