geology exam #3

Downward (troughlike) folds in the Earth's crust.

upward-arching folds

A type of fault where the hanging wall slides downward; caused by tension in the crust

Are caused when rocks are compressed together, the hanging wall slides up, and the footwall slides down (convergent boundary)

Occur when opposing forces cause rock to break and move horizontally.

Stress that squeezes rock until it folds or breaks

pulling apart of the earths crust

force directed parallel to a surface

coming together

Moving apart

A plate boundary where two plates move past each other in opposite directions

The coast lines of South America match the coastlines of Africa (some continents fit together like a jigsaw puzzle)

Hypothesis for seafloor spreading mid-ocean ridges represented tectonic plate factories, where new oceanic plate was issuing from these long volcanic ridges

Scientists had noticed for some time the alignment of magnetic north in many rocks was nowhere close to the earth's current magnetic north. Found from paleomagnetism

When plates of different densities converge, the higher density plate is pushed beneath the more buoyant plate

Convergent

Collision?

The molten magma is more buoyant than the lithospheric plate above it and migrates to the Earth's surface where it emerges as volcanism.

form when oceanic crust subducts beneath other oceanic crust on an adjacent plate, creating a volcanic island arc.

form when oceanic crust subducts beneath continental crust on an adjacent plate, creating an arc-shaped mountain belt.

As an oceanic plate descends, it pulls the ocean floor down into a trench. These trenches can be more than twice as deep as the average depth of the adjacent ocean basin.

Higher density (ocean) crusts get pushed under buoyant crust (lithosphere) it is rigid enough to be pushed down

buoyancy prevents descending

Within the trench, ocean floor sediments are scraped together and compressed between the subducting and overriding plates.

A chain of volcanoes formed above a subducting plate, positioned in an arc shape

Active margins can be convergent or transform margins. A passive margin is the transition between oceanic and continental lithosphere that is not an active plate margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting creates new ocean basins.

Collision

Mid-ocean ridge

Compressional thrust faulting

Continental rifting

Oceanic-oceanic subduction

Oceanic-continental subduction

Layer below the lithosphere this layer moves and flows due to convection currents created by heat coming from the earth's core.

Sometimes known as the lower mantle, subjected to very high pressures and temperatures. These extreme conditions create a transition zone in the upper mesosphere where minerals continuously change into various forms, or pseudomorphs.

Completely liquid

Solid, scientists believe the earth's magnetic field is generated by the circulation of molten iron and nickel within the outer core.

Acasta river area canada acasta gneiss

Iron was in non-oxygenated environment (reducing environment). Once the environment was oxygenated, iron combined with free oxygen to form solid precipitates of iron oxide, such as the mineral hematite or magnetite.

Greenstone belts are considered to represent ancient volcano—sedimentary basins bordered and intruded by granitic plutons

greenstone belts are interpreted as the remains of ancient ocean basins, which were squished between ancient proto-continental terranes

Tonalite-trondhjemite-granodiorite a highly deformed and metamorphosed rock

They were the stable interior of the current continents that were mostly formed in the Archean eon.

Helped date oldest rocks on earth

Meteors

The Big Bang is a theory that discusses the origin of the universe (from a single point source of incredible density and energy) while the Nebular Hypothesis is a theory that discusses the origins of stars and their planetary systems (through the accretion of interstellar gas).

A spinning cloud of dust made of mostly light elements, called a nebula, flattened into a protoplanetary disk, and became a solar system consisting of a star with orbiting planets

A Mars sized asteroid crashed into the Earth causing a chunk to be broken off and pulled into Earths gravitational pull.

Continents develop and grow in several ways as a byproduct of sea floor spreading and subduction?

The major layers of the Earth, starting from its center, are the inner core, the outer core, the mantle, and the crust. These layers formed as the building blocks of Earth, known as planetesimals, collided and collapsed under their own gravity around 4.5 billion years ago. The heaviest elements (like iron and nickel) sank to the core, while the lighter elements (like silicon, oxygen, and carbon), rose to form the mantle and crust.

Stromatolites 3.4 Ga

Cyanobacteria was the first organism to start creating oxygen which is an essential element for life.

Layered structures created when mats of cyanobacteria are smothered by fine calcite mud distributed by wave action in shallow marine environments

The appearance meant that there was an excess of oxygen available. BIFs decline in the rock record as the amount of oxygen in the atmosphere continued to climb. With more atmospheric oxygen available, iron ions were oxidized in terrestrial settings before they were transported to the oceans.

When cyanobacteria put out massive amounts of oxygen into the atmosphere. Iron combined with free oxygen to form solid precipitates of iron oxide, such as the mineral hematite or magnetite

Prokaryotes came first they lack cell nuclei and other organelles. Eukaryotic cells are more complex, having nuclei and organelles. The nuclear DNA is capable of more complex replication and regulation than that of prokaryotic cells

Ancient glaciers left behind three kinds of signatures: (1) striations, (2) tillites, and (3) dropstones. These signatures are found in Neoproterozoic strata

The Ediacaran biota are a diverse assemblage of complex, macroscopic multicellular body and trace fossils. Ediacaran biota represents basal members of some certain invertebrate animal groups, such as cnidarians and mollusks. Others have argued for identification of various Ediacaran forms as giant protists, algae, worms, fungi, or in a phylum of their own. At least some are ANIMALS. They are disc-shaped, frond-like shape, or have bilateral/trilateral symmetry. Oxygen levels in the surface oceans were still increasing and bacteria levels were high in seas. Not still alive today

Rodinia

Laurentia