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109 Cards in this Set
- Front
- Back
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What is the classification and interpretation of the geologic column in terms of formally defined rock units?
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Stratigraphy
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Stratigraphy is based on what?
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The geologic time scale
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A body of rock which is defined by some geologic characteristic (lithology, structures, etc.)
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Facies
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Stratigraphic units which are defined on the basis of physical characteristics are called what?
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Lithostratigraphic units
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The most important type of stratigraphic units are what?
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Lithostratigraphic units
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Stratigraphic units defined on the basis of fossil content are called what?
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biostratigraphic units
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Why are fossils considered reliable to date stratigraphic units?
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Fossils cross lithostratigraphic boundaries.
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What are used to correlate stratigraphic units with the geologic time scale?
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fossils (biostratigraphic units)
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Rock units which are deposited during a specific time interval are called what?
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chronostratigraphic units
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An example of a facies which is composed of chronostratigraphioc units is?
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A submarine fan
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Stratigraphic term used for units of geologic time.
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geochronologic units
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Stratigraphic units defined on the basis of magnetic polarity
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magnetostratigraphic units
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Stratigraphic units which are used to define rocks that don't adhere to the Law of Superposition (i.e. dikes, plutons, etc.)
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lithodemic units
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A section of readily accessible rocks, which define a lithostratigraphic unit.
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stratotype
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The original or subsequently designated standard of reference of a named layered stratigraphic unit or stratigraphic boundary.
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stratotype
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What are three criteria which must be met for a unit to be considered a stratotype?
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1. Must be representative of rock unit.
2. Must be easily accessible 3. Must be well exposed. |
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The most basic unit of lithostratigraphy.
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formation
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The term used to describe a lithologically distinctive, mapable lithostratigraphic unit.
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Formation
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Type of stratigraphic unit which is usually shown on a geologic map
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formation
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Two criteria for a stratigraphic unit to be considered a formation
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1. It must be mappable
2. It must have geographic extent |
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Each stratigraphic formation has a...
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type section (stratotyp)
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Stratigraphic formations are normally named for...
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geographic locations
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A stratigraphic unit of essentially uniform or uniformly heterogeneous lithologic character having intertonguing relationships in all directions with adjacent rock masses of different lithologic character.
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Lithosome
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A formation could be made up of one or more ......
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lithosomes
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The smallest lithostratigraphic unit is a
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bed
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A bed is usually a subdivision of a
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formation.
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what are four characteristics of a bed that Dr. Howard wanted us to know?
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1. usually a single bed of one type of rock
2. Usually contain ore 3. possibly very distinctive 4. subdivision of a formation |
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A stratigraphic unit which is part of a formation but thicker than a bed.
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member
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A stratigraphic unit composed of more than one formation.
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group
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A stratigraphic unit composed of more than one group
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supergroup
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Name the lithostratigraphic units in order from smallest to largest.
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1. bed
2. member 3. formation 4. group 5. supergroup. |
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what is therm used to decrsibe the boundary between two different types of rock units?
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contact
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What are three basic types of contacts?
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1. Conformable
2. Interbedded (interstratified, intercalated) 3. unconformable (unconformity) |
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What is the name of a contact which shows no evidence of a significant loss of time?
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Conformity (conformable contact)
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What are two types of conformities?
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1. Gradational
2. Diastem (minor gap in time) |
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What is the term for a type of contact composed of alternating (interfingering) layers of rock?
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Interbedded (interstratified) contact
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Type of unconformity in which parallel bedded rock unit sit on top of tilted rock units.
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Angular unconformity
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Type of unconformity in which an erosional surface cross-cuts existing rock beds.
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erosional unconformity
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Type of unconformity which develops between sedimentary rocks and older rocks (such as granite bedrocks, etc.)
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nonconformity
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Type of unconformity in which the bedding planes above and below the break are essentially parallel, indicating a significant interuption in the orderly sequence of rock units.
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disconformity
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Sequence which "deepens downward"
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trangressional sequence
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A sequence which represents an incursion of the ocean onto terrestrial rock layers.
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Transgressional sequence
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A sequence of rock units which represents the moving outward of the ocean from terrestrial rocks.
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Regressive sequence
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An assemblage of genetically related facies or lithosomes bounded above and below by unconformities.
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allostratigraphic unit
(i.e. a deltaic sequence bounded by marine limestone below and sandstone above) |
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The characterization or correlation of rock units on the basis of their fossil content
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Biostratigraphy
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Biostratigraphy is based on what/
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Law of Faunal Succession
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Fossils are found worldwide in the geologic record in a definite and predictable sequence or order:
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Law of Faunal Succession
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Fossils in the rock record tend to grade how?
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Upward from relatively simple organisms to more complex organisms.
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Person who first discovered that certain rock units had certain assemblages of fossils.
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William Smith
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Person who classified rock types by the percentage of extant fossil species they contained.
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Lyell
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Time period which contains 90% or more extant species.
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Pliocene
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Time period which contains approximately 18% extant species.
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Miocene
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Time period which contains roughly 3.5% extant species
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Eocene
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Person who coined the term stage for use in classifying rock units based on their fossil content.
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d'Orbigny
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Term used for groupss of rock strata which all contain the same fossil assemblages.
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Stage
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d'Obigny based stage boundaries on what?
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The first or last appearance of a certain fossil.
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Fossil type which is indicative of a certain stage. The stage is generally named after this fossil.
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index fossil
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A biostratigraphic unit defined on the basis of the stratigraphic ranges of fossils.
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biozone
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Three basic types of biozones
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1. Interval zone
2. Abundance Zone 3. Assemblage Zone |
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Term used to describe the body of strata between two first or last occurences of a particular fossil type.
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Interval zone
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The interval between the lowest and highest occurence of a single taxon.
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taxon range zone
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What are three types of Interval Zones?
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1. Taxon Range Zone
2. Concurrent Range Zone 3. Lineage Zone |
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Term used to describe the zone defined by the association of three or more taxa.
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Assemblage zone
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A zone defined by the peak in the abundance of one or more taxa
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Abundance zone (aka acme zone)
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Why is the Abundance (acme Zone) not a reliable dating tool?
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It does not have any evolutionary significance.
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Biozones are ususally named for what?
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1 or two characteristic or common taxa
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A group of one or more biozones is called a what?
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Superzone
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A subdivision of a biozone is called a what?
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subzone
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what are three key things that a fossil taxa must have in order to be a reliable dating tool?
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1. Abundance
2. Geographic extent 3. Rapid-evolution + short-ranging existence |
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What are the two major exincions in the fossil record which Howard wants us to know?
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1. Term Paleozoic
2. Term Mesozoic |
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Organic evolution is important in the fossil record because?
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1.) It results in the first and last appearances of fossil taxa.
2.) can be used to distiguish species that became isolated due to tectonism. |
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what term is used to describe the characteristic of fossils having paleogeographic limits?
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Provincialism
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What is one drawback to using an Assemblage or Acme zone to date strata?
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They usually cross geochronological time boundaries instead of defining them.
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What type of biozone usually produces the most reliable dates for rock strata?
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Interval Zones
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What is the term used to describe bodies of rock which were deposited during a specific time interval?
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Chronostratigraphic Units
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The geostratigraphic equivalent of
a.) eon b.) era c.) period d.) epoch e.) age f.) chron |
a.) eonothem
b.) erathem c.) system d.) series e.) stage f.) chronozone |
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The geostratigraphic equivalent of an eon is?
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eonothem
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The geostratigraphic equivalent of an era is?
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erathem
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The geostratigraphic equivalent of a period is?
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system
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The geostratigraphic equivalent of an epoch is?
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series
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The geostratigraphic equivalent of an age is?
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stage
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The geostratigraphic equivalent of a chron is?
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chronozone
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When we talk about geologic units of time, we use the qualifiers....
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1. early
2. middle 3. late |
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when we talk about rock units which were deposited during a particular unit of time, we use the qualifiers....
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1. upper
2. middle 3. lower |
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Rocks deposited during the early cambrian period are referred to as
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lower Cambrian system
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The two main subdivisions of rocks in geologic time are?
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1. Phenerozoic Eonothem
2. Precambrian Eonothem |
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The three erathems in the geostratigraphic record are:
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1. Paleozoic Erathem
2. Mesozoic Erathem 3. Cenozoic Erathem |
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The systems into which the Paleozoic erathem is divided into are the:
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1. Cambriam system
2. ordovician system 3. silurian system 4. devonian system 5. carboniferous system 6. permiam system |
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The systems into which the Mesozoic erathem is divided into are:
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1. Triassic system
2.Jurassic system 3. Cretaceous system |
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The systems into which the Cenozoic erathem is divided into are:
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1. Paleocene series
2. eocene series 3. oligocene series 4. miocene series 5. pliocene series 6. pleistocene series 7. holocene series |
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Stages and chronozones are named on what basis?
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geographic locality
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What are the three components of the Earth's magnetic field?
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1. Declination
2. Inclination 3. Polarity |
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What is the term used to describe the difference between geographic and magnetic north?
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Declination
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What is the term used to describe the angle of dip made by the Earth's magnetic lines with respect to the surface of the Earth?
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Inclination
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what is the inclination at the equator?
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0 degrees
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What is the inclination at the poles?
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+/- 90 degrees
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What is the configuration of the earth's magnetic field during normal polarity?
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Nmag roughly equal to Ngeog
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What is the configuration of the Earth's magnetic field during reverse polarity events?
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Nmag roughly equal to Sgeog
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What is the term used to describe a period of time greater than 100,000 years of magnetic stability?
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epoch
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what is the term used to describe a period of time less than 100,000 years of magnetic stability?
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Event
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What are the two types of magnetostratigraphy units?
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1. polarity zone
2. polarity subzone |
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What is the magnetostratigraphic unit which coincides with a magnetic epoch?
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polarity Zone
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What is the magnetostratigraphic unit which coincides with a magnetic event?
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polarity Subzone
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Which of the following is composed of siliceous microfossils?
a. breccia b. chert c. feldspathic wacke d. clay-shale |
b. chert
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which of the following is not a chemical sedimentary rock?
a. limestone b. dolostone c. rock gypsum d. diamictite |
d. diamictite
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Organic sediments/sedimentary rocks include all of the following except:
a. peat b. carbonaceous shale c. coquina d. coal |
c. coquina
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Which parameter is a measure of the range in particle sizes in a sample?
a. mean b. sorting c. oblate-prolate index d. mode |
b. sorting
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Which would you least expect to find in a siltstone?
a. slate rock fragments b. feldspar c. granite rock fragmens d. quartz |
c. granite rock fragments
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Very good sorting is most likely found associated with which type of deposit?
a. breccia b. diamicton c. eolian dune e. turbidite |
c. eolian dune
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