Geology 101

Plate tectonics

  • The study of the origin and evolution of the Universe is called ............. cosmology

  • The theory that describes the formation of the universe is called ........big bang. According to this theory, the universe evolved ..........13.8. billion years ago from a very high density and high temperature state and keeps ...........expanding.. since that time.

  • The Solar System (and the Earth) formed about ........4.6.....billion years ago

  • The process of formation of Earth’s layers is called .......differentiation....... The denser layer (composed of primarily Fe and some Ni) is in the middle and it is called .........the core....; it has two parts – solid ........inner..... and liquid ........outer.....

  • The presence of liquid metallic elements in the outer core of rotating Earth creates the Earth’s .......magnetic field......

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

  • The Earth middle layer is called .......mantal....... It is also composed of several layers: the

outermost one is rigid, while the one below - .......asthenosphere...... - is plastic (partially molten), while the rest of the mantle is solid

  • The Earth’s crust can be of two types: ......continental....... and .......oceanic......

  • Continental crust is .......less...... dense than oceanic

  • Continental crust is .......more...... thick than oceanic.

  • The Earth has several different “spheres”: .......lithosphere......sphere –the outermost rigid layer composed of the crust and upper rigid mantle, .....hydrosphere........sphere (ocean, surface and ground waters), ......atmosphere.......sphere (air) composed of mainly ......nitrogen....... and .........oxygen.....

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

  • According to this theory, the lithospheric plates are not static, they move around colliding

with each other

  • The evidence of .......continental drift...... include:

    • Matched fit of continents

    • Climate belts

    • Fossil distributions

    • Rock unit distributions

    • Radiating glacial patterns

    • Paleomagnetic studies

GEOL101, Spring2025

Page 1 of 5

  • The evidence of ........seafloor spreading.... include:

    • Stripped pattern of magnetic field (magnetic reversals)

    • Seafloor ridges and transform faults

  • A lithospheric plate consists of ......crust....... and ......upper mantel.......

  • There are about ......12....... plates, and they move at the velocity of 1 -15 ............./yr

  • Plate tectonics are driven by ........convection currents..... in asthenosphere

  • At .....divergent........-plate boundaries, plates pull apart and ......rifiting or spreading....... occurs.

  • ......convergent.......-plate boundaries result in mountain building.

  • At .....transform........-plate boundaries, plates slide past one another.

  • There were a few supercontinents in the Earth’s history. The latest one was called .......Pangea......, and it started to break apart around .......200...... Million years ago.

Minerals

Mineral 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.

  • Minerals are “.....building blocks........” of rocks

  • There are about .......4,000...... known minerals

  • To be called a mineral, the substance should have .......5......(how many) characteristics:

    • Solid of Liquid? solid

    • Organic or inorganic? inorganic

    • Artificially made of naturally occurring? Natural occurring

    • Defined internal structure or chaotically organized one? Defined structure

    • Defined chemical formula or does not matter? Defined chemical formula

  • Minerals are grouped based on their chemical formula

  • The majority of mineral are .......silicates...... (SiO2)

  • Another large class is .......carbonates...... (CaCO3)

  • Minerals are identified based on their ......anions.......

  • .......color...... is not a good characteristic for some minerals, for example ........quartz..... (SiO2), which can be of many colors, while is very good for others (sulfur is .......yellow......, malachite is ......green.......)

  • The color of the powder that mineral leaves behind is called ......streak........

  • .......luster...... is the way that light interacts with the surface of a mineral. It can be .......metallic...... and ........nonmetallic.....

  • .......hardness...... is measured by the resistance to abrasion. The hardness of .....glass........ is 5.5

  • .......specific gravity.... - the weight of the mineral over weight of equal water volume

  • Crystal habit and crystal form – the way the crystal ......grows.......

  • Fracture vs cleavage – the way the mineral .....breaks........

  • Rocks are ........assemblages..... of minerals

  • Rocks are .......coherent...... (i.e. forming a whole), naturally occurring solid, consisting of an .........assemblage... of minerals, or, less commonly, of ........glass......

  • The rock can be ......glassy.......– composed of glass (example: .......obsidian......), or non-glassy – either ......crystalline....... (made up of crystals welded together) or .....clastic....... (composed of individual grains)

Rocks and Rock cycle

  • There are .....3........ major types of rocks:

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

    • ........igneous.....– are formed by solidification from molten state. They are composed of .......crystals or minerals...... interlocked together (example: granite, basalt), or rarely, of ........glass..... (example: obsidian)

    • .......metamorphic......– are formed in a very high heat and pressure, resulting in a ......transformation....... of a pre-existing rock (examples: marble, slate, gneiss, schist).

  • The ........texture..... of a rock is the size, shape, and arrangement of the grains (for .....sedimentary........

rocks) or crystals (for ......igneous....... and .....metamorphic........ rocks).

  • .......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.

GEOL101, Spring2025

Igneous Rocks

  • Molten rock on Earth’s surface is called ........lava....., beneath Earth’s surface - .......magma.......

  • Melting of solid rocks occurs as a response to changing .......temp......and .........pressure.....

  • ........decompression..... melting occurs at mid-ocean ridges and rifts. .....flux........ melting occurs above subducting plates.

  • Melt composition is controlled by .....partial........ melting (......felsic...... melts first) and ........assimilation..... (blocks of rocks fall into magma and melt). ......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.

  • Magma rises because it is ......buoyant....... and because of pressure from overlying rocks.

  • Movement rates are directly controlled by a magma’s .....viscosity......... Felsic magma is .......more...... viscous than mafic one.

  • If magma solidifies within the rock, ......sills.... (horizontal), ........dikes..... (vertical), ........plutons..... (blob-shaped) and .......laccoliths...... (mushroom-shaped) structures are formed.

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

  • Igneous rocks are categorized based on their .......texture...... and .......composition.......

  • Composition is dependent on the .....source......... Texture is dependent on ......??........

  • .........extruded.... rock cools rapidly, and crystals do not have time to grow large. .....intrused........ rock

cools slowly and have large crystals.

  • ......porfirated?....... texture: both small and large crystals (called .......themophist?......), indicating a initial

.......slow...... cooling followed by ......rapid.......cooling (usually after an eruption)

Sedimentary Rocks and Soil

  • Geologists define .......4...... (how many) sedimentary rock classes:

  • .......clastic......: loose rock fragments (clasts) cemented together

  • .......biochemcal......: cemented shells of organisms

  • ........organic.....: carbon-rich remains of once-living organisms

  • .......chemical......: minerals that crystallize directly from water

  • Processes that break up rock into sediments is called .......weathering......; removal of grains is called .........erosion..... Major erosional agents are: .......water......, ......ice....... and .......wind.......

  • Weathering may be of .........3.... (how many) types: ......physical......., .......chemical...... and ......biological.......

  • Clastic sedimentary rocks are formed when weathering and erosion create ......sediments......., that are later transported, deposited and .....lithification........ (cemented).

  • Clastic sedimentary rocks are classified based on their ......texture....... (grain size, angularity and sphericity. sorting) and ......composition....... (clast composition, character of cement).

  • Biochemical sedimentary rocks are made of sediments derived from the shells of once-living organisms (fossiliferous limestone (mineral .............) and chert (mineral .............)). Page 4 of 5

GEOL101, Spring2025

  • Chemical sedimentary rocks are composed of minerals ......precipitation....... from water solution (.........limestone.... – CaCO3 precipitated from ground water) or ....evaporated......... from seawater (NaCl - .....halite........)

  • Organic sedimentary rocks are made of organic carbon, the soft tissues of living things

(.......coal...... - altered remains of fossil vegetation and ........oil.....- shale with heat-altered

organic matter).

  • ......breccia....... is clastic sedimentary rock with angular fragments of rock in finer-grained matrix. The one with rounded pebbles of rock is called ......conglomerate........

  • .......arkose......—sand and gravel with abundant feldspar.

  • ....sandstone.........—clastic rock made of sand-sized particles.

  • Silt-sized sediments are lithified to form ........siltstone...... Clay-sized particles form mudstone or .......shale.......

  • ....sedimentary structures.........are features that form when sediments are deposited. They include bedding, ripple marks and dunes, cross-bedding, graded beds, mudcracks, etc.

  • Sedimentary structures tell us about the ......paleoenvironment......., such as glacial, desert, coastal, fluvial environments.

  • Sedimentary ......basins....... are special places that accumulate sediment. They may be ........foreland..... (in front of mountains), .....intracontinental........ (far away of tectonic boundaries), ....passive-margin......... basins (created as a result of continental rifting) and .............basins (formed at the edges of continents that are not tectonic-plate boundaries).

  • A sea-level fall or ....regression......... shifts environments toward the basin. A sea-level rise or ......transgression....... shifts depositional bets landward.