Geo Lec MidTerm 1

tested and confimred hypothsis, complex and accepted fact

WWII bounce sound waves to the ocean floor.

most abumdant on earths surface

• Crust: shell fractured brittle; mantle: mushy solid (silly putty); Outer Core: liquid metal; Inner Core; solid metal
• Asthenophere: silly putty squishy liquid

it is a universal statemnt of fact, often written as a math equation; 10 to the 0 = 1, 10 to the 1 = 1. 10 to 2 = 100

1. make an obersvation or identify problems. 2. make hypothesis to explain observations, make prediction based on hypothsis, 3. gather evidence to test the hypothsis. 4. reject hypotheis (ideally all but one).... Remaining hypothesis is the most probable.

untested explanation, educated guess

1930 German meteorologist. proposed continents were not fixed and they were once fit together called Pangaea.

Pangaea fragmented into peices into separate continents that drift apart.

When continents drift apart, new ocean floor forms between them

Continents move toward each other when the old ocean floor between them sinks back down into the Earth's interior

The earths lithosphere consists of 20 different pieces that slowly move relative to each other.

The grand unifying theory of geology, because it successfully explains great many geologic phenomena. It is the theory the plates move relative to each other.

a record of earths magnetic field in the past. This provided proof of continental drift and contributed to the plate techtonic theory.

Circulation of liquid iron alloy in the outer core of the earth generate a magnetic field. Two ends with opposite polarities.

an imaginary arrow that intersets the surface of the planet at two points known as the magnetic poles.

One process happens when lava (molten rock) cools to form basalt. As it cools and solidifies, time magnetite crystals begin to grow. At first thermal energy causes the magnetic dipole to go crazy and then they settle to permanent parallelism with the Earths magnetic field.

The successive positions of dated paleopoles trace out a curving line. the continents move relative to a fixed pole. The continents must move with respect to each other. This proved Wegeners was theory of continental drift was correct.

Divergent: The floor beneath all major oceans includes abyssal plains (broad, flat regions in the ocean), mid-ocean ridges (elogate submarine mountain ranges). The crest of the MOR's are the ridge axis. All MOR's are symetrical. Bathymetry is a mirror image on the other side.

late 1950 Hess suggest the seafloor had molten rock below it at the ocean ridges which furthered the idea of plate techtonics

Lithosphere: crust plus the top plus the cooler top of the upper mantle.

Their thickness. On average, continental lith has a thickness of 150km. The crustal part of the continental is lower in density. The crustal part of the oceanic lith is on 7-10 km and is highly dense mafic rock

The earths lithosphere is divided into plates that move relative to each other and relative to the underlying asthenosphere. Plate movement occurs 1-15cm a yr. The rocks along the plate boundaries undergo deformation as the plate moves away or into its neighbor. The earth surface constantly changes.

2 oceanic plates move apart by the process of sea floor spreading. When the plates move apart, new floor forms. Takes place a submarine mountian range called a mid ocean ridge that rises 2 km above the adjecent abyssal plains of the ocean..

Mid-Ocean Ridge MORS MOVING AWAY

magnemitet rocks will aligh with magnetic field; paleomagnatism; polar wander; apparent polar wonder; continental drift;

in the navy hypothesised that heat flow at ridge (magma implies new crust moved up at MOR), sediment depth confirms MOR is younger. Theory for sea floor spreading came up with sebduction

What is the sinking process of one plate?

Oceanic lithosphere is denser that sthenopsphere and can sink through the asthensphere.

No, it is too bouyant. the low density rocks acts as a preserver not allowing it to sink

THe belt of the earthquakes in a downgoing plate.

an oceanic boundary, an oceanic plate sinks into the mantle beneath the edge of another plate. This process allows the two plates to move toward wach other and ocean basins to close. Trenches and volcanic arcs delinineate convergent boundaries.

A boundary at which on lithoisphere plate slips laterally past another. A vertical fault on which the slip direction parallels the earths surface.

a column of very hot rock rising up through the mantle to the base of the lithosphere.

A hotspot track. When the overlying plate moves, it slowly carries the volcano off the top of the plume.

Both, ex. Hawaiian Island and Yellowstone national park

the process during which two buoyant pieces of lithosphere converge and squeeze together. Ex Himalayas and the Alps, India running into Asia.

a linear belt in which continental lithosphere undergoes rifting or pulls apart. The lithosphere stretches horizontally so it thins vertically.

What drives plate movement?

the force that drives plates away from a mor. it is caused by the fact that the ridge is elevated relative to the regions of oceanic plate away from the ridge.

The force that downgoing plates (or slabs) apply to oceanic lithosphere at a convergent margin. Stanton def: cold dense rock working its way back to earth, pulls rock behind it.

crust, mantle, outer core: liquid metal; inner core; solid metal

density driven vertical or cyclical movement of material in response to heat.

A various times during Earths history the polarity reversed. It alternates between normal polarity and sometimes it is revered polarity.

Homogeneneous, naturally occuring, solid, definable chemical composition, crystal lattuce.

the same chemical composotion throughout

orderly; atoms or molecules oxygen in a pyramid = techagyron, sheet, piling on (glass not mineral)

crystal is the structure; mineral is the material;it extends in three directions; break crystal and you get a mineral.

3 ways: crystallization/freezing; preceptitation from ions in water disolved state to solid state (PPT); solid under higher temps (rock burial);

Shape and color

refers to the color of a powder produced by pulverizing the mineral. scraping it on an unglazed ceramic plate

how mineral reflects light, metallic, looks like metal; mom-metallic - glassy, waxy pearl earthy

measure of the relative ability of a mineral to resist scration. The atoms of a strong mineral are more tightly bound than a soft mineral. Diamond is the hardest mineral out there. Minerals are listed in a hardness of 1 to 10 via Friedrich Mohs.

listed 1 to10 10can scratch all materials.

crystals grow from seed. grow out from center, stop growing at barriers. Shape controlded by shape of barrier

• represents the density of the mineral to the weight of water.
• Weight of volume of mineral OVER weight of volume of water. < > more or less dense that water. Density of mineral compared to the density of water. Water density is 1.

most silicate minerals in the crust consist of a building block which is the silicane oxygen tetrahedron. The basic building blocks of silicates.

Silicates, carbonates, native metals, oxides, Sulfur bearing, halides

sedimentary rock - erosian, metamorphic, heat pressure; igneous-melt

texture and mineral composition

granite=slowcooling-large crystal; ryolite=fast cooling= small crystals, obsidian=very fast cooling=glass (no crystals, glass mising a latuce structure.

measure of the angles of two adjecscent faces on crystal. 120 degrees is always a quartz

A general shape or growth; referest to the shape ofa single crystal with well-formed crystal faces. or to the character of an aggregate of many well formed crystals that grew together as a group. Catergories: needle like, columar radiating, primatic, fiberous, cubic

if a mineral breaks to form distinct planar surfaces that have a specific orientation in relation to the crystal structure. it has a cleavage plane

Different minerals frature in different ways. Depending on the internal arrangement of the atoms

Materials that have no cleavage at all

Most abundant at surface. silica tetrahedron, SIO4; 90% of continental crust; Quartz is most abundant silicate. Silicate= quartz, talc, opal, mica, beryl, feldsbar

Electrical charge, likes to attach to other minerals; wil FIZZ, DOUBLE VISION; Carbonate ion;

consist of pure masses of a single metal. Copper and gold.platinum

Mixed with iron and oxygen; RUST OXIDATION; cobtain hematite and magnetite

metals bonded to sulfur; gypsum/walllboard; gelena/pyrite Foolsgold; epsonite/Epson Salts.

Contains anything chloride, flourine, iodine = florite, italite (tablesalt)

if the pressure affecting hot mantle decreases while the temperature remains unchange, magma forms; magma also forms at locations where chemicals called colatiles mix with hot mantle rock. the rock mets or flux melting; melting as a result of heat transfer of rising magma forms magma

Felsic (or silicic), intermediate, Mafic, Ultramafic

Contains silicon and oxyfen, which bonds to form the silicon-oxygen tetrahedron. it contains other elements too.

Different rock sources; partial melting; magma mixing; assimilation or cross contamination

first, magma rises because it is less dense then surrounding rock; second the weigh of over lying rock creates pressure at depth that squeezes magma upward

rock formed by the freezing of magma underground

Rock that is formed by magma above ground, after it flows or explodes out (extrudes) onto the surface and comes into contact with the atmosphere or ocean

Fine grained - aphanitic; coarse grained - phanetic; porphyritic - two crystal sizes (chocolate cookie looking); glassy

1920s Norman L. Bowen, began a series of experiements to determine how silicate minerals crystalize from melt. He created a diagram of order in which minerals freeze.

the process by which a magma becomes progressively more silicic as it cools, because early-formed crystals settle out.

the different compositional classes are distinguished on the basis of silica content- ultramafic, mafic, intermediate or felsic. The different textural classes are based coarse or fine. Color

CREATED AT MANTLE/HOTSPOT; DENSE; almost all dark; little silica; first to crystalize; high temps; Peridotite and olivine

CREATED AT OCEANIC-CONTINENTAL; convergent plate boundary; less dense; made of oceanic lithosphere; dark in color, not a lot of green and grey; High in FE/mg; GABBRO/BASALT

COMBO of madic and felsic, happens at MOR's; Convergent plate boundary; less dense, MOUNTIAN RANGES; OCEANIC CONTINENTAL locations; mid gray (salt & pepper); DIORITE?ANDESITE

CONTINENTAL RIFTS; CONTINENTAL LITHOSPHERE; divergent plate boundaries; silicates, lover in mg/fe; light in color (grey or pnk) ; granite/rhyolite

Fragmental rocks composed of debris that have been blasted out of a volcano or thrown out in a fountain. Pyro meaning fire in greek.

large rounded cone. cools in mid air.

glassy; floats

parcles that explide violently out of volcanoes.

erups violently out of volcanos.

decrease in pressure; hot rock rises, lower in pressure; melting occurs. Temperature unchanged.

Gases; h20 and co2

transfer of heat from a magma chamber. Some of surround rock.

decompression; addition of volitiles (gases); heat transfer

where land forming a MOR, continental rifts example. it is the the largest fresh water lake in the world. land is being stretched. NOT A PLATE BOUNDARY

pluton, batholith, laccolith, sill, dike

BIG BLOB; old magma that has made its way to the surface

HUGE HUGE HUGE BLOB or bunch of blob (plutons), most of the sierras are made of of batholiths

UFO shaped; flat on bottom; oval on top

horizontal intrusion

vertical intrusions

volcanos, magma chamber, crater, caldera,

a space below ground filled with magma

conduit to the crust that is cracked.

a circluar or a fissure

it is the opt of a volcano; yellow stone

felsic, viscous, violent, caldera colapse, EX: crater lake oregon; pyroclastic event

gently sloping mafic basaltic, runny lava, high in iron and magnesium, HUGE, no violent. low viscosity, Hawaii is the largest shield volcano on earth. kilauea: 50 eruptions since 1823.

Flows with warm, pasty surfaces wrinkle into smooth, glassy, rope like ridges

If the surface layer of the lava freezes underneath, it becomes a jumble of sharp, angular fragments, creating a rubbly flow. It is foot slashing

Step 1. Observation: italy's 1970's, geos working on 65mya rocks. KT boundary 65 mya ago rocks. Iriduim Spike (not common on earth) Step 2. Hypothesis, asteriod struck earth, kicked up debris, blocked sunlight, stopped photosynthesis Step 3: Gather evidence, all at 65mya, clay layer weathered glass, "the smoking gun" tektites, shocked quartz, iridium spikes, new animals. Step 4: Reject hypothesuis: stupidity, change climate, dinosur disease, mammals outcompeted dinosaur, dinosaur flatulence (ALL NOT TRUE). Scientific consensous: what ever is most probable given the evidence in hand: AN ASTROID DID IT>