What forms when magma cools?
Igneous rock
The rock cycle begins with the cooling of magma to form igneous rocks.
What is the process that transforms igneous rock into metamorphic rock?
Heat and pressure
Compression and heat cause the transformation of igneous rock into metamorphic rock.
What must happen to igneous rock to become sedimentary rock?
Erosion into sediments
The rock erodes into smaller pieces that are deposited and compacted.
Name the three types of rocks.
- Igneous rocks
- Sedimentary rocks
- Metamorphic rocks
Each type of rock forms through different geological processes.
Describe the Asthenosphere.
Upper mantle layer, weak plastic layer
Tectonic plates move on this layer.
What causes convection currents in the Asthenosphere?
Temperature differences in magma
These currents lead to magma movement.
Define Igneous activity.
Creation of igneous rocks through cooling of magma
This process is essential in the rock cycle.
What is the relationship between magma placement, cooling rate, and texture of igneous rocks?
- Hot magma rises
- Slow cooling = coarse-grained
- Fast cooling = fine-grained
The cooling rate affects crystal size in the rock.
Identify and describe igneous rocks based on texture.
- Granite: coarse-grained, big crystals
- Rhyolite: fine-grained, small crystals
- Basalt: fine-grained, smooth
- Obsidian: glassy, smooth
- Scoria: rough, full of holes
- Pumice: very light, full of tiny holes
Texture is determined by the cooling rate of magma.
Differentiate between Mafic and Felsic igneous rocks.
- Mafic: darker, richer in magnesium and iron
- Felsic: lighter, richer in silica
This classification is based on mineral composition.
Define weathering.
Breaking rocks into tiny pieces
This is the first step in sediment formation.
What is erosion?
Movement of weathered pieces by wind, water, ice, or gravity
Erosion transports sediments to new locations.
Define sedimentary rocks.
Rocks made from sediments pressed and cemented together
They often form in layers.
Why are most sedimentary rocks found in areas where there was once an ocean?
Oceans collect sand, mud, and shells
These materials pile up and form sedimentary rock over time.
What are the steps of lithification?
- Compaction
- Cementation
These processes turn sediments into sedimentary rock.
Name two cementing agents.
- Silica
- Calcite carbonate
These agents help bind sediments together.
Describe Clastic, Chemical, and Organic sedimentary rocks.
- Clastic: fragments of pre-existing rocks
- Chemical: minerals precipitated from water
- Organic: remains of living organisms
Each type is classified by its composition.
Identify different types of sedimentary rock samples.
- Sandstone
- Shale
- Chemical Limestone
- Rock salt
- Coal
- Organic Limestone
These rocks vary in composition and formation.
Explain why only sedimentary rocks may contain fossils.
They don’t conserve heat or pressure
This allows for the preservation of fossils.
What are Index Fossils used for?
Determine the relative age of rock layers
They indicate that different rocks are about the same age.
Define metamorphism.
Process of existing rocks changing into new types due to heat and pressure
This process leads to the formation of metamorphic rocks.
Differentiate between Foliated and Nonfoliated metamorphic rocks.
- Foliated: has bands or stripes
- Nonfoliated: lacks layers
The texture is determined by the arrangement of minerals.
What happens when you heat and pressurize a rock?
It changes into a metamorphic rock
The minerals may rearrange or form new patterns.
