Igneous, Sedimentary, and Metamorphic Rocks

Igneous, Sedimentary, and Metamorphic Rocks

Igneous, Sedimentary, and Metamorphic Rocks

When dealing with rocks we can classify them into three different categories: igneous, sedimentary, and metamorphic. I kind of want to go into a definition of each one of those. Give a couple examples. Igneous rock is formed when a hot magma cools beneath the ground or lava cools above the ground. If it’s hot magma it’s got to cool beneath the ground, if its lava it has to cool above the ground to form larger fine-grained crystalline, porous or glassy rocks of varying chemical -competition- composition.

There are several things they can form it could form large grain crystalline and fine-grain crystalline and porous or glassy rocks, and they’re going to have varying chemical composition. If you’ve ever seen rock that was black and really porous, that was an example of igneous rock and that was lava that cool above the ground near a volcano. A couple of examples of this would be granite and pumice. Then we have sedimentary rock which forms from previously weathered and eroded material which may have been igneous, sedimentary, or metamorphic rock.

It could be any of the three types of rocks and it’s just that type of rock has weathered and eroded, and it forms into what we call sedimentary rock. The sedimentary rock you’re dealing with could have used to been sedimentary rock or it could have used to have been metamorphic rock or igneous rock. A couple of examples of this is dolomite and limestone. I’m going to talk about those a little bit more in just a second.

This weathering material deposits out layers and eventually becomes compacted, or chemically solified -that occurs- chemically solidified into rock or both could happen it could become compacted and chemically solidified into rock. Now, sedimentary rocks, like the ones that talked about like dolomite and limestone, can also form from the compaction of calcium carbonate exoskeletons of aquatic organisms. Then sediments can also form from the precipitation of salts from evaporating bodies of water.

Then we have metamorphic rock which is altered, partially re-melted and generally highly crystalline igneous, sedimentary, or even older metamorphic rocks that have undergone an extreme amount of heat and compression. All metamorphic rock is altered partially re-melted and generally highly crystalline. From there it could be igneous, it could be sedimentary, or it could be metamorphic if it’s older and has undergone an extreme amount of heat and compression. There’s lots of options for what a metamorphic rock is made up as well.

Now anthracite coal is a highly metamorphous coal. Anthracite coal has gone very often through the metamorphosis process. Organic sales and dikes can produce contact -metamorphi- metamorphism and immediately adjacent rock while -lifting of- uplifting mountain ranges result in large scale regional metamorphosis and you can see a number of ways it can be formed. Couple of examples of metamorphic rock is slate as well as marble. That’s a look at the three types of rocks igneous, sedimentary, and metamorphic.



by Mometrix Test Preparation | Last Updated: August 20, 2019