Science #1: Rocks Flashcards
What is Metamorphic rock?
A metamorphic rock is a result of a transformation of a pre-existing rock. The original rock is subjected to very high heat and pressure, which cause obvious physical and/or chemical changes. Examples of these rock types include marble, slate, gneiss, schist.
They can be formed by pressures deep inside the Earth, by tectonic processes such as continental collisions, or when they are heated up by an intrusion of hot molten rock called magma from the Earth’s interior.
Metamorphic rocks are made by either heating up or squashing the earth’s crust. They are often found in mountainous regions. One example is slate. Slate was originally a black mud laid down on the bottom of the sea or lake. Fossils can sometimes be found in it but they are often squashed. Other common metamorphic rocks are called marble, gneiss, schist.
What are Igneous Rocks?
Igneous rock (derived from the Latin word ignis meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet’s mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition.
Of all the rocks you can see on Earth, what percent has already been recycled?
Igneous and metamorphic rocks make up 90–95% of the top 10 miles of the Earth’s crust by volume.
[This means 95% of every rock you can see on the Earth has gone through a volcano!]
[1] Igneous rocks form about 15% of the Earth’s current land surface.
What determines the type of rock that comes out of a volcano?
Rocks can be Extrusive or Intrusive.
Extrusive rocks cool on the outside of the volcano.
Intrusive rocks, such as Granite, cool on the inside the crust of the volcano.
Intrusive igneous rocks are formed from magma that cools and solidifies within the crust of a planet, surrounded by pre-existing rock (called country rock); the magma cools slowly and, as a result, these rocks are coarse-grained. The mineral grains in such rocks can generally be identified with the naked eye. Intrusive rocks can also be classified according to the shape and size of the intrusive body and its relation to the other formations into which it intrudes. Typical intrusive formations are batholiths, stocks, laccoliths, sills and dikes. When the magma solidifies within the earth’s crust, it cools slowly forming coarse textured rocks, such as granite, gabbro, or diorite.
What does a rock cycle look like?
All Rocks go through a recycle, or rock cycle over and over.
These cycles take many millions of years to complete.
What are the steps of the rock cycle?
- When a volcano erupts, lava hardens and forms igneous rocks.
- After a great deal of weathering and displacement, these rocks break down and settle in sediment beds, eventually forming sedimentary rocks.
- As the new rock moves deeper into the Earth, it is exposed to heat and pressure which changes it into metamorphic rock.
- The process is cyclical because these metamorphic rocks eventually melt to the original state__magma, which will again become igneous rock.
NOTE: So, to get Marble for your kitchen counter top, you must grab the Marble before it goes through a volcano again. Once it goes through the volcano, it is Igneous rock once again!
What are the three layers of the Earth’s interior?
- Crust: The outermost layer of the Earth, this hard outer shell is made up of rock and is anywhere from a few miles to 20 miles thick.
- Mantle: The upper and lower mantle are located below the crust and are made up of solid and molten rock. The thickest of the 3 layers, the mantle is approximately 1,800 miles thick.
- Core: The core of the Earth is separated into two parts: outer and inner. The outer core is comprised mostly of liquified iron and nickel, and spans 1,400 miles. The inner core of solid, hot iron and nickel is about 750 miles in diameter.
So just think, the core’s diameter is a greater distance than driving from St. Louis to Los Angeles, Calif.
What is the difference between Magma and lava?
Only a slight difference.
Magma refers to what is still underground, but lava is the term used for molten rock that is above ground due to a volcanic or seismic event.
What are the major eras of the Earth?
- Precambrian. 4,500 million years ago. Oceans form and single celled and multi-celled organisms.
- Paleozoic. Earliest forms of sea life, plants, insects, and eventually early reptiles and amphibians. This era was 291 millions years long.
- Mesozoic. The age of reptiles. This 186 million year period included the dinosaurs, the first birds, and the first mammals.
- Cenozoic. The current era has spanned 66 million years thus far. Mammals and birds thrive and evolve, including the introduction of the first humans.
