Igneous Rocks
List the 3 textures of igneous rocks
2. Fine-Grained
3. Course-Grained
Recall and define the two parts of lithification.
Lithification occurs through compaction and cementation.
Compaction: Sediments are buried and have accumulating sediments above them Pressure increases cementing them together.
Cementation: groundwater flows in through pore spaces. Ions precipitate and minerals are left behind, hardening clasts together.
Describe what a metamorphic rock is.
Metamorphic rocks are pre-existing rocks that are altered by intense heat and pressure.
When does the rock cycle end?
It never ends. There is constant recycling of earths materials.
Compare and Contrast intrusive and extrusive igneous rock formations.
Intrusive rocks form when magma is trapped below the earth's surface, cooling very slowly as it rises to the surface.
Extrusive rocks form above earths surface, when magma exits the earth and cools very quickly.
Explain what sorting and rounding tell us about a sedimentary rock.
Rounding of grains gives us clues to the amount of time a sediment has been in the transportation cycle. Rounding increases with transport distance and time.
High energy forms of transportation carry larger fragments. As the energy decreases, heavier clasts are deposited and lighter clasts continue to be transported. Sorting gets better as larger clasts are left behind and smaller clasts are carried away
What kinds of rocks can become metamorphic rocks?
Both sedimentary and igneous rocks can be put under heat or pressure to become metamorphic rocks.
The sorting is poor.
Group these pictures into categories. (Pictures on slideshow)
Fine grained= pumice and basalt
Course Grained= granite
Glassy= obsidian
What are the features of a clastic sedimentary rock?
Clastic rocks are made up of clasts (articles that have been broken and transported). They are identified based on the size of their clasts.
What is a characteristic of the rock gneiss?
Gneissic banding.
True/false: a rocks texture is the roughness/feeling of its surface.
False, texture is the size, shape, and arrangement of grains/clasts within the rock.
A volcano has just erupted. Predict what will happen that magma, and provide an example of what type of rock it may form.
The magma will cool very quickly, leaving us with a fine-grained, extrusive rock. That rock could be pumice or basalt.
Order the following steps of sedimentary rock formation:
Compaction/cementation, rocks, transport, weathering, sediments, deposition, sedimentary rocks.
Rocks -> weathering -> sediments -> transportation -> deposition -> compaction/cementation -> sedimentary rocks.
How would you breakdown the cause of foliation?
A rock with randomly oriented minerals experiences extreme pressure, which forces the randomly oriented minerals to align evenly.
What would occur if I took an igneous rock and applied heat and pressure?
Name this rock and hypothesize how this rock might have formed. (picture on slide show)
Pumice, it forms when a volcano erupts and cools rapidly. The vesicles in the rock form from trapped gas bubbles that were trapped due to rapid cooling.
Consider a situation where frost-wedging might occur.
Water seeps into cracks on rock, freezes, and expands, creating a larger crack. Repeated cycle eventually breaks rock apart. Ex: Rain a climate that experiences freezing temperatures overnight. Rain fills cracks during the day and freezes at night.
Elaborate on the location of metamorphic rock formation.
Metamorphic rocks form deep in the planet’s crust, they are often exposed on the surface of the Earth. This happens because of geologic uplift and the erosion of the rock and soil above them.
What would occur if a sedimentary rock went through weathering and erosion?
You would be left with sediments.