GEOL 1400 - Midterm 1 latest updated version with 100% accurate solutions + rationales

What is geology?

Study of the earth, other planets, moons, etc. Divided into physical geology (earth materials and processes) and historical geology (origin and evolution of the earth, continents, oceans, atmosphere, and life).

Characteristics of the Universe

All matter and energy, no center and no edges, cooling, expanding, permeated by background radiation

Big Bang Theory

Theory that all matter and energy originated from one starting point. Happened 14 Ga years ago. The universe is expanding and permeated by background radiation. Has not yet been falsified.

Doppler Shift

Light and sound. Higher frequency when approching, lower pitch when going away. Light blue when approaching, red when going away. Same thing is happening to universe.

Solar Nebula Theory

Solar system formed by starting as a gas ball, flattening, swirling, and clumping into planets.

Terrestrial Planets

Solid, rotate slowly, less dense metal core, formed at higher heat, closer to the sun

Jovian Planets

Non-solid, faster rotation, dense hydrogen and metal cores, formed at lower heat, further from the sun

Homogenous Accretion Theory

Early earth was probably uniform density, but spinning. Over time, heavy stuff falls towards the middle. Creates iron/nickel core, lighter mantle, mineral/silicate crust. Dense metal core creates heat, helps differenciate layers.

Minerals

naturally occuring, inorganic crystalline solids, particular chemical composition, characteristic crystalline structure

Rock

Interlocking/bonded grains of minerals

Outcrop/Exposure

Exposed rock surfaces

Silicate rock

Rock made of silica, 1/3 of all known minerals, 90% of the earth's crust (ex: quartz, potassium, feldspar)

Carbonate rock

Rock composed of carbonate minerals, calcite (shells/skeletons), (ex: limestone)

Aphanitic Igneous Rock

Extrusive. Slow cooling, smaller grains, volcanic.

Phaneritic Igneous Rock

Intrusive. Rapid cooling, bigger grains, plutonic.

How is sedimentary rock formed?

Made of sediment. Weathering forms sediment, erosion transports sediment. Transported by water, glaciers, wind. Precipitation of minerals from solution. Compaction of plant and animal remains.

Sedimentary Rock

Rock made of sediment

Lithification Process

Sediments accumulate, compacted by weight, cemented by minerals

Detrital Sedimentary Rocks

Composed of clasts (fragments of pre-existing rocks), ex: sandstone

Chemical/Biochemical Sedimentary Rocks

Minerals extracted from solution form by inorganic chemical processes or organisms. Crystalline or clastic texture. Ex: limestone.

Metamorphic Rocks

Igneous/sedimentary rocks altered by heat and pressure.

Causes of Metamorphism

Heat, pressure (lithostatic and differential), fluid activity

Types of Metamorphism

Regional (large areas, deep), dynamic (faults), contact (high heat)

Compositional Metamorphism

New minerals formed

Textural Metamorphism

Minerals are aligned

Foliated Metamorphism

Combination of textural (minerals aligned) and compositional (new minerals), layered pattern.

Continental Drift Theory

Wegener, Pangea. Developed by Du Toit. Evidence from continental fit, similarity of rock sequences, glacial evidence, and fossil evidence.

Seafloor Spreading

Seafloor separates at oceanic ridges, new crust is formed by upwelling magma, magma cools, new forced ocean crust moves laterally away from ridge.

Magnetic Reversals

When a volcano erupts, minerals align themselves with the Earth's magnetic poles. Slightly off of geographic centre. Over time, this pole shifts, and the minerals align the opposite way.

Theory of Plate Tectonics

Large segments of lithospheric plates move relative to one another.

Earth's Core

Small solid inner liquid portion, made of iron and some nickel

Earth's Mantle

Surrounds core, includes solid lower mantle, partially molten asthenosphere that flows slowly, and solid upper mantle. Made mostly of peridotite.

Earth's Crust

Lithosphere, including thinner oceanic crust and thicker continental crust

Lithosphere

Upper mantle, continental crust, and oceanic crust

Mantle Cell Convection

Heat in the earth's core is decayed by radioactive elements, moves out of core via material transfer in the liquid mantle towards the surface. Cooling material becomes dense enough to travel laterally under the lithosphere and begins to sink. Reheats and rises again.

Divergent Plate Boundaries

Formation of new lithosphere, most often found in ocean ridges. Ex: mid-Atlantic Ocean Ridge

Convergent Plate Boundaries

Three types. Cause of deformation, volcanism, mountain building, metamorphism, earthquakes, mineral deposits.

Transform Plate Boundaries

Faulting and sliding plates. Friction. Causes earthquakes. Ex: Juan de Fuca.

Oceanic-Oceanic Convergence

Ocean trench. Ex: Japan, back-arc spreading

Oceanic-Continental Convergence

Subduction zone, plates sliding under continent. Ex: South America, volcanoes, earthquakes.

Continental-Continental Convergence

Crusts hitting each other and lifting. Mountain building, ex: Himalayas.

What is the role of Plate Tectonics in the Rock Cycle?

Convergent boundaries create mountains, mountains erode and produce sediment, sediment is transported and buried and lithified, internal heat/pressure melts material, igneous rocks are created, igneous and sedimentary are altered and form metamorphic rocks.

Uniformitarianism

Laws of nature remain unchanged throughout time, processes observed today also operated in the past

Actualism

Application of modern processes to ancient systems

Stratigraphy

Focus on composition, origin, age relationships, and geographic extent of layered rocks

Superposition

Oldest strata are at the bottom in an undisturbed sequence of strata

Original Horizontality

All strata are horizontal when they form

Original Lateral Continuity

Strata are originally unbroken flat expanses, can be interrupted by erosion

Cross-Cutting Relationships

Intrusive igneous rocks or faults are always younger than the rock they invade

Inclusions and Components

Rock fragments within another body are older than the including body of rock

Unconformities

Substantial interval of time when erosion occurred, rather than deposition

Angular Unconformities

Underlying strata are angled relative to overlying strata

Disconformities

Separate parallel bedded rocks via an erosion surface

Nonconformities

Erosion surfaces cut into igneous or metamorphic rock, overlain by a sedimentary bed

Relative Dating

Order of deposition of a body of rock based on position

Absolute Dating

Number representing the time a body of rock was deposited, uses radiometric dating

Lithostratigraphic Correlation

Correlation based on rock types and sequences. Rock units are in correlation without regard to age.

Principle of Fossil Succession

Vertical ordering of fossils in geological record

Index Fossil

Easily identifiable fossil with wide geographic distribution and short geologic range, useful for determining the relative ages of strata in different areas

Process for identifying Absolute Age?

Radioactive molecules (parent isotopes) of certain elements locked into igneous rocks during cooling. After crystallization, parent isotopes begin to decay. Decay at constant exponential rate. Half parent will survive, half will decay to daughter.

Half-Life

Interval of time for half of parent isotopes to decay

Half life of carbon?

5730 years

Chronostratigraphy

Combines relative dating (lithostratigraphy and biostratigraphy) with radiometric dating methods. Integration of multiple methods generates the most robust signals to put dates on rock strata (layers). Sequences of rocks are broken up into blocks of time based on the fossils they contain. Volcanic layers (geologically "instantaneous") given the absolute context.

Why is it difficult to date sedimentary rocks absolutely?

Because they contain older rocks, including metamorphic rocks

Fossils

Prehistoric remains/traces, usually preserved in sedimentary rocks

Body fossil

Fossilized physical part of an organism

Trace fossil

Fossilized trace that an organism left behind. Ex: tracks, trails, nests, burrows, feces, bioturbation.

What kind of information can fossils provide?

Information about ages of rocks, depositional environments, and evolution. Also relative ages of strata in separated columnar sections of rock.

Basic Fossilization Requirements

Oxygen-poor environment, low energy setting, and rapid burial in fine-grained sediment. Favorable conditions include durable skeleton, living where burial sediment is likely, and avoiding decay, scavenging, and metamorphism.

Examples of factors that effect fossilization

Scavenging, depth, salinity, pH, oxygenation, climate (temperature and moisture), wave/current action (transport/abrasion), deposition environment (materials and rates)

Taphonomy

Study of all factors that affect organisms from time of death to time of discovery as fossils

Best locations for fossilization

Sedimentary environments, coastal (sand dunes, rivers, sand banks, shores), reefs, marine/deep ocean, caves/sinkholes/sediment traps/preditor traps/tar pits

Unaltered Remains

Body fossils preserved in amber, tar, or by freezing or mummification

Altered Remains

Body fossil. Organic material replaced, but shape and structure remains through replacement, carbonization, permineralization, or recrystallization.

Molds

Type of fossil where organic material no longer exists

Casts

Type of fossil where organic material no longer exists, but leaves impression which is filled in by other materials

Evolution

Changes in heritable traits in a population over time. Can result in new species.

Populations

Groups of individuals of the same species that live together

Natural Selection

Mechanism for evolution. Organisms possess heritable variations, some traits are more favorable for certain environments. Not all young survive to maturity. Individuals with favorable variations are more likely to survive to adulthood and pass on variations.

"Survival of the fittest"

Heritable variations leading to differential reproductive success

Artificial Selection

Selective breeding of domestic animals and plants

Alleles

Alternate forms of genes that control the same trait. Dominant and recessive.

Genetics

Pair of genes controls traits. Genes that control traits do not blend during inheritance. Genes are located within a strand of DNA, organized into the parallel chromatids of a chromosome. Complete sets of chromosomes have different versions called alleles. Meiosis (combining/splitting DNA) and mitosis (duplication of cells)

Mutations

Change in chromosomes/gene that affect hereditary information.

Chromosomal Mutations

Genetic mutations that affect large segment of the chromosome. May be harmful, beneficial, or have no effect. Caused by mutagens (chemicals, radiation, extreme temperatures) or may be spontaneous.

Point Mutations

Genetic mutations that affect a single gene

Causes of genetic variation

Sexual reproduction and mutations account for most of the variations in population

Genetic Drift

Random change in gene in a population due to chance. Affects small populations more than large.

Species

Natural populations of similar individuals that can interbreed and produce fertile offspring. Excludes asexual organisms.

Speciation

Formation of a new species from ancestral ones

Phyletic Gradualism

Accumulation of minor changes in a population, giving rise to new species.

Punctuated Equilibrium

Stasis/minor changes in species over long periods, punctuated by rapid changes over a short time

Extinction

Dying out or exterminating of a species. Background extinction is ongoing. Mass extinction is rarer, but cull species more quickly. Occurs periodically. Gives rise to opportunities for the evolution of new species.

Micro-Evolution

Evolutionary changes within a species, ex: insects developing resistance to pesticides. Micro-evolution creates macro-evolution over time.

Macro-Evolution

Changes such as a new species, genera, families, orders, classes. Ex: amphibians are descended from fish.

Divergent Evolution

Diverse groups of animals from one common ancestor.

Convergent Evolution

Species with similar shapes because of their environment, with no recent common ancestor

Parallel Evolution

Two related species that have made similar evolutionary adaptations after their divergence from a common ancestor

Embryology

Embryos of many vertebrates are similar for most of their development. Evidence for evolutionary relationships.

Homologous Structures

Presence of anatomical structures in different groups of organisms that have some ancestral origin, but now serve a different function