Geology 101 final exam

cosmology

The study of the origin and evolution of the Universe is called

Big Bang

The theory that describes the formation of the universe is called

13.8 billion

According to the Big Bang theory, the universe evolved … years ago

Expanding

The universe evolved from a very high density and high temperature states and keeps

4.5 billion years ago

The solar system and the earth formed about

Differentiation

The process of formation of earth’s layers is called

The core

The earth’s denser layer (composed of primarily Fe and some Ni) is in the middle and it’s called

Inner core , Outer core

The core has two parts— solid … and liquid …

Magnetic field

The presence of liquid metallic elements in the outer core of rotating earth creates the earth’s

Reversal

The magnetic field is not static, the magnetic poles switch periodically in the process called magnetic

Mantle

The earth’s middle layer is called

Asthenosphere

The mantle is composed of several layers: the outermost one is rigid, while the one below … is plastic (partially molten), while the rest of the mantle is solid

Continental and Oceanic

The earth’s crust can be of two types

Less

Continental crust is … dense than oceanic

More

Continental crust is … thick than oceanic

Lithosphere

The earth has several different “spheres”: the outermost rigid layer composed of the crust and upper rigid mantle

Hydrosphere

The earth has several different “spheres”: ocean, surface and groundwaters

Atmosphere

The earth has several different “spheres”: air composed of mainly oxygen and nitrogen

Air

Composed of mainly oxygen and nitrogen

Alfred Wegener

is believed to be a father of the theory called plate tectonics.

Plate Tectonic theory

According to this theory, the lithospheric plates are not static, they move around colliding with each other

Continental drifting

The evidence of … include:

-matched fit of continents

-climate belts

-fossil distributions

-radiating glacial patterns

-paleomagnetic studies

Seafloor spreading

The evidence of … include:

-stripped pattern of magnetic field (magnetic reversals)

-seafloor ridges and transform faults

the crust and upper rigid mantle

A lithospheric plate consists of

20

How many plates are there?

1 - 15 cm/yr

Plates move at the velocity of

Convection

Plate tectonics are driven by … in the asthenosphere

Divergent-plate

At … boundaries, plates pull apart and rifting occurs

Convergent-plate

… boundaries result in mountain building

Transform-plate

At … boundaries plates slide past one another

Pangea

The latest super continent was called

2000 million years ago

Pangea started to break apart around

Minerals

Is a naturally occurring, inorganic solid with a specific internal structure. It has a chemical composition that varies within certain limits and can be expressed by a chemical formula.

Calcite CaCO3

In limestone and marble: gives off CO2 (fizzes) in acid

Halite NsCl

“Rock salt”, evaporation of dense brine

Gypsum CaSO4 x H2O

Scratch with fingernail; used in drywall

Pyrite FeS2

“Fools gold”, cubic crystals main source of sulfur in acid mine drainage

Quartz SiO2

Framework silicate; concoidal fracture, harder than glass

Feldspar

most common mineral in earth’s crust; framework silicate, also contains sodium, potassium, calcium; harder than glass

Mica

sheet silicate; perfect cleavage in one direction

Olivine

isolated silicate; density varies with iron and magnesium content

Clay

sheet silicate usually forming tiny crystals; key constituent of mudstone and many soils; may swell when wetted

Glass (non-mineral)

has no ordered crystal lattice (a chaos of ions); made by quenching a melt (no time to form lattice)

“buliding blocks”

Minerals are … of rocks

4,000

There are more than … known minerals

Five

To be called a mineral, the substance should have … characteristics

Solid

solid or liquid? (minerals)

Inorganic

Organic or inorganic? (minerals)

Naturally occurring

Artificially made of naturally occurring? (minerals)

Defined internal structure

Defined internal structure or chaotically organized one? (minerals)

Defined chemical formula

Defined chemical formula or does not matter? (minerals)

Their chemical formula

Minerals are grouped based on …

-the majority of mineral are silicates (SiO2)

-another large class is carbonates (CaCO3)

Physical properties

Minerals are identified based on their

Color

… is not a good characteristic for some minerals, like quartz.

Color

… is a very good characteristic for minerals like sulfur (yellow) and malachite (green)

Streak

The color of the powder that a mineral leaves behind is called

Luster

… is the way that light interacts with the surfaces of a mineral (metallic or non-metallic)

Hardness

… is measured by the resistance to abrasion

Glass

The hardness of … is 5.5

Specific gravity

… the weight of the mineral over weight of equal water volume

Growth

Crystal habit and crystal form—the way the crystal …

Breaks

Fracture vs cleavage—the way the mineral …

Assemblages

Rocks are … of minerals

Coherent

Rock are … naturally occurring solid, consisting of an aggregate of minerals, or, less commonly, of glass

Glassy

The rock can be … —composed of glass (ex: obsidian)

Crystalline

The rock can be non-glassy— … (made up of crystals welded together)

Clastic

The rock can be non-glassy… (composed of individual grains)

3

How many major types of rocks are there?

Sedimentary rocks

Are formed from clasts (or grains) of pre-existing rocks and are held together by cement, or fomred by mineral precipitation the solution (such as rock salt)

Igneous rocks

Are formed by solidification from molten states. They are composed of crystals interlocked together (ex: granite, basalt) or rarely of glass (ex: obsidian).

Metamorphic rocks

Are formed in a very high heat and pressure, resulting in a transformation of a pre-existing rock (ex: marble, slate, gneiss, schist)

Texture

The … of a rock is the size, shape, and arrangement of the grains.

Thin section

… is a very thin slice of rock allowing to study details of the rock texture

Rock cycle

is an idealized cycle of processes undergone by rocks in the earth’s crust.

Rock cycle

involves igneous intrusion, uplift, erosion, transportation, deposition as sedimentary rock, metamorphism, remelting, and further igneous intrusion.

Lava

Molten rock on earth’s surface is called?

Magma

Molten rock beneath earth’s surface is called?

Temperature and pressure

Melting of solid rocks occurs as a response to changing…

Decompression

melting occurs at mid-ocean ridges and rifts.

Flux

melting occurs above subducting plates.

Partial melting

Melt composition is controlled by … (silca melts first)

Assimilation

Blocks of rocks fall into magma and melt altering its composition.

Xenoliths

Are chunks of wall rock incorporated into the magma.

Mafic minerals

(rich in Fe and Mg) are first to crystallize and last to melt

Felsic minerals

(rich in Si, Al, K) crystallize last and are first to melt

Buoyant

Magma rises because it is … and because of pressure from overlying rocks

Viscosity

Movement rates are directly controlled by a magma’s …

MORE

Felsic magma is … viscous than mafic one.

Sills

If magma solidifies within the rock, … (horizontal) structures are formed.

Dykes

If magma solidifies within the rock, … (vertical) structures are formed.

Plutons

If magma solidifies within the rock, … (blob-shaped) structures are formed.

Laccoliths

If magma solidifies within the rock, … (mushroom-shaped) structures are formed.

Cooling

The rate of … depends on the size, depth and composition of an intrusion.

compositon and texture

Igneous rocks are categorized based on their …

Source material

Composition is dependent on the …

Cooling rate

Texture is dependent on …

Extrusive

… rock cools rapidly, and crystals do not have time to grow large.

Intrusive

… rock cools slowly and have large crystals.

Porphyritic texture

… both small and large crystals indicating an initial slow cooling followed by rapid cooling (usually after an eruption)

Four

How many sedimentary rock classes are there?