Types of Rocks Flashcards
Sedimentary rocks
They form from particles of other rocks or remains of plants and animals that are pressed and cemented together.
What is clastic sedimentary rock?
They form from particles of rock. Examples: Shale, Sandstone, Conglomerate, and Breccia
What are the two ways that nonclastic sedimentary rock forms?
They form from chemical precipitation or organic activity.
Sediment
Small, solid pieces of material that come from rocks or living things
Erosion
Destructive forces such as heat and cold, rain, waves, and grinding.
Deposition
The process by which sediment settles out of water or wind carrying it.
Compaction
The process that presses the sediment together.
Cementation
While compaction is taking place, the minerals in the rock slowly dissolve.
Uses of sedimentary rocks
- Limestone and sandstone cut easily into blocks for building.
- The White House is built of sandstone.
- Limestone is important for smelting ores.
Nonclastic rocks from chemical precipitation
A type of sedimentary rock… Chemical rocks form when minerals that are dissolved in a solution crystallize. They can also form mineral deposits left when seas and lakes evaporate. Examples of this are halite and gypsum.
Nonclastic rocks from organic activity
Sedimentary rocks that form from a once-living thing over time
Examples:
-Coal: Remains of swamp plants buried in water. The weight of the layers of plants squeeze the decaying plants.
-Limestone: Hard shells of living things produce some kinds of limestone (coral, clams, oysters, snails). When the animals die, the shells pile up as sediment on the ocean floor.
-Chalk is a type of limestone from microscopic skeletons on the ocean floor.
What causes an igneous rock to have a fine-grained texture, and what is the texture like?
Caused by rapid cooling lava; these “smooth” rocks have small crystals.
What causes an igneous rock to have a course-grained texture, and what is the texture like?
Caused by slow cooling magma; these “rough” rocks have large crystals.
Porphyritic texture
A rock with large crystals scattered among small crystals (looks like Jell-o with chunks of fruit mixed in)… it happens when an intrusive rock cools in two stages. Large crystals form slowly, and then when the magma moves closer to the surface, small crystals form quickly.
Grain pattern
Grains often form patterns. Some rocks have a grain pattern of flat layers like pancakes. Others have wavy, swirly patterns.
What does the word igneous mean (comes from the Latin word “ignis”)?
Ignis means fire.
What is an igneous rock formed from?
It is formed from magma or lava.
Extrusive rock
Forms from lava that erupted on to the earth’s surface.
Intrusive rock
Forms from magma that hardened below the earth’s surface.
Uses of igneous rocks
They are hard, dense, and durable, and they have been used throughout history for tools and building materials.
- Obsidian was used by N.A.s for making very sharp tools. It looks like black glass.
- Granite has been used for building materials (statues in Ancient Egypt, fortresses by the Incas, bridges and buildings in the U.S., etc.)
- Basalt is crushed for gravel
- Pumice is abrasive (rough) and is good for cleaning and polishing. It floats on water
Metamorphic rocks
They form from existing rocks that have changed their form because of heat, pressure, or ?
What does meta mean in Greek? What does morphosis mean in Greek?
Meta mans change and morphosis means form.
What can metamorphic rock form out of?
Sedimentary rock, igneous rock, or other metamorphic rock
Foliated
means “leaf” in Latin - refers to repetitive layering in metamorphic rocks
What does the igneous rock called granite turn into under heat and pressure?
The metamorphic rock called gneiss
What does the sedimentary rock called shale turn into?
The metamorphic rock called slate
What is metamorphic rock used for?
Marble and slate are both great materials for building. They can be used for flooring, roofing, walkways, and chalk boards.
