Chapter-2 Historical Geology Flashcards
Study of changes to earth and life in time and space.
Historical Geology
Types of ages
Relative Time (Relative Age) Absolute Time (Absolute Age)
Measurement of time using comparison methods.
Relative Time ( Relative Age )
Measurement of time using actual numbers.
Absolute Time ( Absolute Age )
Measuring Earth’s Relative Age
Use of Rocks
Use of faults to determine relative rock age layers abd the order in which event happened
Measuring Earth’s Absolute age
Radioactive Dating
Half-life
The breaking down of atoms to form different isotopes of the same element or completely new element.
Radioactive Dating
The amount of time it takes for half of the original atoms to decay.
Half-life
Fundamental Theories of Historical Geology
Uniformitarianism
Catastrophism
Suggested that the landscape developed over long periods of time through a variety of slow geologic and geomorphic processes.
Theory of Uniformitarianism
Theory proposed by James Huttonin 1785, which was based only on natural history, which was later expanded by Charles Lyell in the 1830s.
Theory of Uniformitarianism
Lyell’ uniformitarianism propositions, according to Reijer Hooykas in 1963
Uniformity of Law
Uniformity of Methodology
Uniformity of kind
Uniformity of Degree
Laws of nature are constant across time and space.
Uniformity of Law
Appropriate hypotheses for explaining the geological past are those with analogy today.
Uniformity of Methdology
Past and present causes are all of the same kind, have the same energy, and produce the same effects.
Uniformity of Kind
Geological circumstances have remained the same over time.
Uniformity of Degree
Theory that says: The idea that the Earth has been affected by sudden, short-lived, violent events that were sometimes worldwide in scope.
Theory of Catastrophism
First popularized by Georges Cuvier on the 19th century, which proposed that new life forms had moved from other areas after local floods.
Theory of Catastrophism
Geological epochs had ended woth violent and sudden natural catastrophes such as great floods, formation of major mountain chains or asteroid impact.
Theory of Catastrophism
formerly Cretaceous-Tertiary (K-T) extinction event, about 66 million years ago
Cretaceous-Paleogene Event
a large planetismal somehow impacted the early earth, blew out rocky debris, remelted it and formed the moon , about 4.5 billion years ago.
Giant Impact Theory
distinct surface between two unlike bodies of rocks.
Contact
single layer/bed of rock
Startum
multiple layers/beds of rocks
Strata
Study of Strata
Stratigraphy
a body of rock with distinctive structure that is bounded by contacts
Formation
Locations or proportions where rocks are exposed at the earth’s surface
Outcrop/Exposure
Formulate by Nicolaus Stenoin 1669, a Danish physician, to help him make sense of the rocks of Tuscany, Italy and the various objects contained within them.
Fundamental Principles of Historical Geology
In any undeformed sequence of sedimentary rocks, each bed is younger than the one below it and older than the one above it.
Steno’s Law of Superposition
Sedimentary rocks are horizontal because yhe original sediments were horizontal.
Steno’s Law of Original Horizontality
Starta originally extended in all directions until they thinned to zero at their edges of deposition. Therefore, matching strata on opposite sides of a valley, or continent can be correlated.
Steno’s Law of Lateral Continuity
Invading igneous rock is always younger than the rock it intrudes.
Steno’s Law of Cross-Cutting Relationships
Similar to the intrusive relationships, it states that the fault is younger than the rock itself.
Steno’s Law of Intrusive Relationships
gaps in the geologic taht may indicate episodes of crustal deformation, erosion, and sea level variations.
Unconformity
Types of Uncoformities
Angular Inconformities
Disconformities
Nonconformities
are those where an older package of sediments has been tilted, truncatedby erosion, and than a younger package of sediments was deposited on this erosion surface.
Angular Unconformity
an erosion surface between two packages of sediment, but the lower package of sediments was not tilted prior to deposition of the upper sediment package.
Disconformities
are unconformities that separate igneous or metamorphic rocks from overlying sedimentary rocks.
Nonconformities
Paleozoic era – age of invertebrates
Cambrian period Ordovician period Silurian period Devonian period Carboniferous period Permian period
Mesozoic era – age of dinosaurs & reptiles
Triassic period
Jurassic period
Cretaceous period
Cenozoic era – age of mammals
Tertiary period
Quaternary period
