Geology Exam 3

according to currently available geologic evidence, life appeared on the Earth about ___ ago

3.5 billion years

the oldest known rock found on Earth is dated at ___ years old

4.03 billion

formation of the earth beginning of the paleozoic era beginning of the mesozoic era end of the mesozoic era

4.5 billion years ago 541 million years ago 252 million years ago 66 million years ago

we live in the ____ epoch, the ___ period, and the ____ Era

Holocene quaternary cenozoic

faunal succession

William Smith's principle or law stating that fossil species succeed one another in a definite and recognizable order; in general, fossils in progressively older rock show increasingly greater differences from species living at present

inclusion

a fragment of rock that is distinct from the body of igneous rock in which it is enclosed

soil

a layer of weathered, unconsolidated material on top of bedrock often also defined as containing organic matter and being

cross cutting relationships

a principle or law stating that a disrupted pattern is older than the cause of disruption

disconformity

a surface that represents missing rock strata but beds above and below that surface are parallel to one another

flow

a type of movement that implies that a descending mass is moving downslope as a viscous fluid

talus

accumulation of broken rock at base of a cliff

numerical age

age given in years or some other unit of time determined by using radiometric dating

what are the ways the nuclei of radioactive isotopes can change

an alpha emission a beta emission electron capture

the event that may have caused the extinction of dinosaurs was ___

an asteroid impact on Earth

nonconformity

an unconformity in which an erosion surface on plutonic or metamorphic rock has been covered by younger sedimentary or volcanic rock

angular unconformity

an unconformity in which younger strata overlie an erosion surface on tilted or folded layered rock

turbidity current

an underwater debris avalanche is also known as a ___

examples of unconformities

angular unconformity disconformity nonconformity

rank the following types of mass wasting from most rapid to slowest

avalanche mudflow earthflow creep

physical continuity

being able to physically follow a rock unit between two places.

formations

bodies of rock considerable thickness with recognizable characteristics that make each distinguishable from adjacent

why wouldnt you use carbon isotopes to date the oldest rocks on earth

carbons half life is too short

the ancestry of the hominids dates back to the beginning of the ___ Era, the age of mammals.

cenozoic

the presence of a nonconformity indicates ___

considerable gap in the rock record erosion to significant depths great amount of uplift

the fastest type of flow is a ___

debris avalanche

correlation

determining time equivalency of rock units. rock units may be correlated within a region, a continent, and even between continents.

which of the following are a result of alpha decay

ejection of 2 protons and 2 neutrons from a nucleus atomic mass number decreases by 4 atomic number decreases by 2

which type of radioactive decay involves the incorporation of an electron into a proton, forming a neutron

electron capture

rank the different divisions of geologic time based upon the length of time covered with the longest at the top

eon era period epoch

most uncomformities represent periods of ____

erosion

mass wasting is commonly classified by the type of movement. A ___ is mass wasting that involves the material moving downslope as a viscous fluid

flow

solifluction

flow of water saturated soil over impermeable material

mudflow

flowing mixture of debris and water usually moving down a channel

index fossil

fossil from a very short lived species known to have existed during a specific period of geologic time

a _ is a scientist who specializes in dating rocks

geochronologist

permafrost

ground that remains permanently frozen for many years

What indicates the presence of a disconformity

if certain fossil beds are absent portion of geologic time is missing presence of a weathering surface at the top of a layer

shear strength

in mass wasting the resistance to movement or deformation of material

earth

in mass wasting, soil in which fine grained particles are predominant

shear force

in mass wasting, the component of gravitational force that is parallel to an inclined surface

determining the age of a rock through its radioactive elements is called

isotopic dating

a disconformity is the hardest unconformity for geologists out in the field to detect because___

it often appears to be just another sedimentary contact (or bedding plane) in a sequence of sedimentary rock

a distinctive layer, known as ___ bed can be used to correlate rocks over great distances

key

volcanic mudflows and debris flows are often called

lahars

which of the following is the general term used for the slow to rapid descent of rock or soil

landslide

mud

loosely used for silt and clay, usually wet

debris flow

mass wasting involving the flow of soil (unconsolidated material) in which coarse material (gravel,boulders) is predominant

rotational slide

movement along a curved surface in which the upper part moves vertically downward while the lower part moves outward also called a slump

mass wasting

movement caused by gravity in which bedrock rock debris or soil moves downslope in bulk

slide

movement of a relatively coherent descending mass along one or more well defined surfaces

difference between mud and earth

mud has high content of water clay and silt

paleozoic cenozoic mesozoic

old life new life middle life

how does a disconformity form?

older rocks eroded away parallel to the horizontal bedding plane; renewed deposition later buried the erosion surface

What evidence can be used to determine that the granite is younger than the tilted layers and older than the horizontal layers

pebbles of granite presence of inclusions cross-cutting relationships contact metamorphism principle of superposition

rank the geologic periods of the paleozoic, with the most recent on the top

permian carboniferous pennsylvanian mississippian devonian silurian ordovician cambrian

geologists look for __ as a way to correlate rock units found in different places

physical continuity

what time interval covers the majority of geologic time

precambrian

superposition

principle or law stating that within a sequence of undisturbed sedimentary rocks, the oldest layers are on the bottom and the youngest on top

lateral continuity

principle that states that an original sedimentary layer extends laterally until it tapers or thins at its edges

match the species with the geologic time interval they are known for precambrian paleozoic mesozoic cenozoic

prokaryotes,algae, soft body trilobites dinos mammals

which of the following are a result of electron capture

proton in the nucleus captures an orbiting electron

the spontaneous nuclear change of isotopes with unstable nuclei is called ____ and can be measured with a gelger counter

radioactive decay

rockslide

rapid sliding of a mass of bedrock along an inclined surface of weakness

rockfall

rock falling freely or bouncing down a cliff

which of the following can be used to correlate rock units between two areas

rock type

the type of mass wasting that occurs when a block of bedrock breaks off a cliff is a ___

rockfall

True about isotopes of a given element

same number of protons different number of neutrons different atomic masses

the order of formation of angular unconformity

sedimentation folding erosion renewed deposition of sediment

earthflow

slow to rapid mass wasting in which fine grained soil moves downslope as a very viscous fluid

what materials are the dominant components of mudflows

soil water sand silt clay

what are true regarding the geologic time scale

standard scale that is used worldwide based on fossil assemblages it was first created using relative relationships

which of the following types of surfaces are susceptible to landslides?

steeper parts of the ocean floors slopes in arid regions where plant cover is sparse steep rocky cliffs along the coast

paleontology

study of fossils

unconformity

surface that represents a break in the geological record, with the rock unit immediately above it being considerably younger than the rock beneath

Contacts

surfaces separating two different rock types or rocks of different ages

___ is the large amount of geologic time that occurred before the Paleozoic

the Precambrian

original horizontality

the deposition of most water-laid sediment in horizontal or near-horizontal layers that are essentially parallel to Earth's surface

translational slide

the descending mass moves along a plane approximately parallel to the slope of the surface

landslides

the general term for a slowly to very rapidly descending mass of rock or debris

actualism

the principle that the same processes and natural laws that operated in the past are those we can actually observe or infer from observations as operating at present. under present usage, uniformitarianism has the same meaning as actualism

which of the following are a result of beta decay

the release of an electron from a nucleus

finding several species of fossils rather than just one, in the same rock layer is more useful for correlation with other rock layers because ___

the sediment must have been deposited at a time when all the species represented existed

relative time

the sequence in which events took place (not measured in time units).

fall

the situation in mass wasting that occurs when material free falls or bounces down a cliff

some fossil species are of little value to geologists for correlation because __

the species thrived during too large a portion of geologic time

half life

the time it takes for a given amount of a radioactive isotope to be reduced by one-half

the half life of an isotope is equal to ___

the time it takes for half the parent isotopes to decay

the boundaries between the three eras of the standard geologic time scale re defined by ___

the two great mass extinctions

relief

the vertical distance between points on Earths surface

it is possible to state with confidence that the rocks at locations A and B are part of the same unit because

they are physically continuous with each other

sudden event that may trigger mass wasting of a hillside is a ____

trigger

debris

unconsolidated material (soil) in which coarse-grained fragments predominate

correlation by similarity of rock types is more reliable if __

unusual sequence of rocks is involved

debris avalanche

very rapid and turbulent mass wasting of debris air and water

rock avalanche

very rapidly moving turbulent mass of broken up bedrock

creep (soil creep)

very slow continuous downslope movement of soil of debris

using the principle of cross cutting relationships, it is possible to determine that the dike is ____ than the granite but ___ than the foster city formation

younger older