Metamorphic Rock and Igneous Rocks
THESIS STATEMENT: geologists classify rocks based on how the rocks were formed. Rocks can be classified into three categories on the basis of their formation: igneous rocks, sedimentary rocks and metamorphic rocks.
I. The first type is igneous rocks (from the Greek word for fire) which are formed from molten rock (magma) and lava. A. Formation 1.coming up of magma through cracks 2. forming a layer on surface or filling other cracks 3. cooling forming a very hard igneous rock 4. magma on the surface of the earth, lava _ basalt B. Importance 1. geologically important
- showing characteristics of a specific tectonic environment
2. allowing tectonic reconstitutions
II. The second type is sedimentary rock which is formed by small particles or sediments.
A. Formation
1.sediments
- sand, mud, dead sea animals, weathered rock
2. sediments deposited in layers & become solid rock over millions of years as squeezed by the weight of other deposits B. Importance 1. covering three quarters of the mass of continents 2. important resources concentrated within them _ coil, oil, groundwater, iron ore
3. containing important information about the history of the earth
III. The third type is metamorphic rocks formed from igneous or sedimentary rocks that have been changed, or metamorphosed, into a new rock.
A. Formation
1. forming as a result of high pressures or temperatures deep inside the earth
a. changing of sandstone into quartzite & changing of limestone into marble
- not as hard as igneous rocks but can be heavy
b. slate, schist, gneiss B. Importance
_ providing valuable information about the temperatures & pressures occurring at depths within Earth’s crust
In conclusion, igneous, sedimentary and metamorphic rocks are the three main types of rocks. Rocks are classified by mineral and chemical composition, by the texture of the elements and by the natural processes that formed them.
I. The first type is igneous rocks (from the Greek word for fire) which are formed from molten rock (magma) and lava. A. Formation 1.coming up of magma through cracks 2. forming a layer on surface or filling other cracks 3. cooling forming a very hard igneous rock 4. magma on the surface of the earth, lava _ basalt B. Importance 1. geologically important
- showing characteristics of a specific tectonic environment
2. allowing tectonic reconstitutions
II. The second type is sedimentary rock which is formed by small particles or sediments.
A. Formation
1.sediments
- sand, mud, dead sea animals, weathered rock
2. sediments deposited in layers & become solid rock over millions of years as squeezed by the weight of other deposits B. Importance 1. covering three quarters of the mass of continents 2. important resources concentrated within them _ coil, oil, groundwater, iron ore
3. containing important information about the history of the earth
III. The third type is metamorphic rocks formed from igneous or sedimentary rocks that have been changed, or metamorphosed, into a new rock.
A. Formation
1. forming as a result of high pressures or temperatures deep inside the earth
a. changing of sandstone into quartzite & changing of limestone into marble
- not as hard as igneous rocks but can be heavy
b. slate, schist, gneiss B. Importance
_ providing valuable information about the temperatures & pressures occurring at depths within Earth’s crust
In conclusion, igneous, sedimentary and metamorphic rocks are the three main types of rocks. Rocks are classified by mineral and chemical composition, by the texture of the elements and by the natural processes that formed them.