Geology

How do tectonic plates interact with each other?

Through Convergent (Towards eachother), Divergent (Away from eachother), and Transform boundaries (Sliding Against eachother).

Continental vs. Oceanic:

Continental is THICKER, LESS DENSE, made of GRANITE-LIKE ROCK, FLOATS HIGHER ON THE MANTLE. Oceanic is THINNER, MORE DENSE, made of mostly BASALT, SINKS LOWER ON THE MANTLE.

Where is ocean crust created?:

Divergent Boundaries- Specifically mid-ocean ridges.

What is Mafic (Magnesium+Iron-rich) and Felsic (Feldspar+Silica-rich)?:

They describe the composition of igneous rocks, especially how much magnesium, iron, and silica they contain.

What is some evidence for continental drift?:

Puzzle-like fit of continents, Fossil evidence, Rock formations and mountain ranges.

How does plate tectonics affect the formation of the various rock types?

Igneous: These form from the cooling and solidification of magma or lava.

Sedimentary: These form from the accumulation and compaction of sediments.

Metamorphic: These form when existing rocks are altered by heat, pressure, or chemically active fluids—without melting.

What defines a mineral?

Naturally Occurring, Inorganic, Solid, Definite Chemical Composition, Ordered Internal Structure.

How do we identify minerals?

Luster (Metallic), Hardness, Color, Streak, Cleavage and Fracture, Crystal Form, Special Properties.

What’s an isotope?

is a version of a chemical element that has the same number of protons but a different number of neutrons in its nucleus.

Which igneous rocks are intrusive vs extrusive and why.

Intrusive: Form Undergound, SLOW COOLING ALLOWS LARGE CRYSTALS, Coarse-Grained texture (Granite, Diorite, Gabbro), Plutonic activity.

Extrusive: From at or near the surface, RAPID COOLING RESULTS IN SMALL OR NO VISIBLE CRYSTALS, Fine-grained or glassy texture (Basalt, Rhyolite, Obsidian, Pumice), Volcanic Activity.

Felsic Rocks-

High In Silica, Light-colored (white, pink, or light gray), Lower density and higher viscosity magma, Form in continental crust (Convergent boundaries; Granite)

Mafic Rocks-

Low in Silica (Rich in Magnesium and iron), Dark-Colored (Black, dark green), Higher density and lower viscosity magma, Form at divergent boundaries (Mid ocean ridges (Basalt).

Types of Volcanos-

Sheild, Composite, Cinder Cone.

Why some volcanoes are more explosive than others?

Silica content, Gas Content and Pressure, Magma Viscosity.

What is the VEI index?

Volcanic Explosivity Index, is a scale used to measure the size and intensity of explosive volcanic eruptions

What are different soil layers called?

O Horizon – Organic Layer

Rich in decomposed plant and animal material (humus). Dark in color and found mostly in forested areas.

🌿 A Horizon – Topsoil

Contains a mix of minerals and organic matter. This is where most plant roots grow and biological activity occurs.

🏜 E Horizon – Eluviation Layer

Often pale and sandy, this layer has been leached of minerals and organic matter. It’s not always present.

🧱 B Horizon – Subsoil

Zone of accumulation where minerals like iron, clay, and calcium carbonate collect. Less organic material than above.

🪨 C Horizon – Parent Material

Made of partially weathered rock. It’s the source of the soil above but contains little to no organic matter.

🧊 R Horizon – Bedrock

The solid rock layer beneath all others. It hasn’t undergone soil formation processes.

How abrasion effects sediment

Rounding, Size Reduction, Sorting

How do we classify sedimentary rocks?

Composition & Formation Process. GRAIN SIZE AND SORTING.

Depositional environments for different kinds of sedimentary rocks: Where would you find a sandstone being deposited?

Beaches (Well Sorted), River channels. Desert Dunes

Sedimentary Structures-

Bedding and Stratification, Ripple Marks, Crossbedding, Graded Bedding, Mudcracks, Sole Marks, Bioturbation.

Describe how a sediment that begins as a weathering piece of granite on top of a mountain evolves and matures as it is transported from the Rocky Mountains all the way to the Gulf of Mexico. How does it’s texture and composition change?

Colliding continental plates can create mountains, they’ll end up being pushed up and eroded, the erosion will result in sedimentary rocks somewhere

Regional vs Contact

Regional: Occurs over large areas, high pressure and temperature, foliated rocks (slate, schist), Orogenic belts, directed pressure.

Contact: Localized, driven by heat, non-foliated rocks (marble), Forms a metamorphic aureole, Minerals recrystallized.

Types of parent rocks-

Igneous- Granite, Basalt

Sedimentary- Shale, Limestone, Sandstone

Metamorphic- Slate

What Is Numerical Age Dating?

Also called absolute dating, it provides a quantitative age—like “this rock is 250 million years old”—using scientific techniques. This contrasts with relative dating, which only tells us whether something is older or younger than something else.

Magma can fill in fractures and faults in bedrock that will then harden in big "sheet like" structures. What are these structures called?

Dikes

How do we know that granite was a magma that cooled and turned into a rock underground?

 

It is made out of large crystals that we can see with our eyes.

A magma or lava that cools and turns into a rock is called a__________type of rock. 

Igneous

Oceanic crust is________ while continental crust is____________

Mafic, Felsic

_________sedimentary rocks made up of other broken rock fragments.

Clastic

After a sediment has been deposited and buried, what still has to happen for it to become a sedimentary rock?

Cementation

What are the two major properties that effect the formation of metamorphic rocks

Heat and pressure

Regional metamorphism creates what type of texture seen in metamorphic rocks?

Foliation

A break in time in continuous sedimentary rock layers that is due to erosion is called?

 

Unconformity