Historical Geology Flashcards
– placing rocks in their proper sequence of formation, first, second, third, and so on.
Relative Dating
– it states that in an underformed sequence of sedimentary rocks, each bed is older that the one above it and younger than the one below.
Law of Superposition
- it means that layers of sediment are generally deposited in a horizontal position
Law of Original Horizontality
When a fault cuts through other rocks, or when magma
intrudes and crystallizes, we can assume that the fault or intrusion is younger than the rocks affected
Principle of Cross Cutting
these are pieces of one rock unit that are contained within another. The rock mass adjacent to the one containing the inclusions must have been there first in order to provide the rock fragments. Therefore, the rock mass containing inclusions is the younger of
the two
Inclusions
represents a long period during which deposition ceased, erosion removed previously formed rocks, and then deposition resumed.
Unconformity
It consists of tilted or folded sedimentary rocks that are
overlain by younger, more flat-lying strata
Angular Unconformity
are more common but usually far less conspicuous because the strata on either side are essentially parallel
Disconformity
the break separates older metamorphic or intrusive igneous rocks from younger sedimentary strata
Nonconformity
the remains or traces of prehistoric life. An important inclusions in sediment and sedimentary rocks
Fossils
an interdisciplinary science that blends geology and biology in an attempt to understand all aspects of the succession of life over the vast expanse of
geologic time
Paleontology
the small internal cavities and pores of the original structure are filled with precipitated mineral matter
Petrified
the cell walls and other solid material are removed and replaced with mineral matter.
Replacement
Created when a shell or other structure is buried in sediment and then dissolved by underground water,
Mold
It occurs when fine sediment encases the remains of an organism
Carbonation
- If the film of carbon is lost from a fossil preserved in fine-grained sediment, a replica of the surface that may show considerable detaail
Impression
created when hollow spaces are subsequently filled with mineral matter
Cast
these are the traces of prehistoric life
Trace Fossil
animal footprints made in soft sediment that was later lithified
Tracks
fossil dung and stomach contents that can provide useful informationpertaining to food habits of organisms
Coprolite
highly polished stomach stones that were used in the grinding of food by some extinct reptiles
Gastroliths
an English engineer and canal builder who discovered that each rock formation in the canals he worked on contained fossils unlike those in the beds either
above or below
William Smith
These fossils are widespread geographically and are limited to a short span of geologic time, so their presence provides an important method of matching rocks of the same age
Index Fossil
contains the protons and neutrons of an atom and is orbited by electrons.
Nucleus
number of protons in the nucleus.
Atomic Number
derived by adding the protons and neutrons in an atom’s nucleus
Mass Number
Varieties of the same element that have different mass numbers; their nuclei contain the same number of protons but different numbers of neutrons
Isotopes
The spontaneous decay of certain unstable atomic nuclei
Radioactivity
an unstable isotope of an element
Parent
the isotopes resulting from the decay of the parent
Daughter Product
The procedure of calculating the absolute ages of
rocks and minerals containing certain radioactive isotopes
Radiometric Dating
The time required for half of the nuclei in a sample to decay
Half Life
dating recent events with the use of carbon-14
radioactive isotopes
Radiocarbon Dating
The dating and study of annual rings in trees
Dendrochronology
represent the greatest expanses of time
Eons
a major division on the geologic time scale
Era
characterized by a somewhat less profound change in life-forms as compared with the eras
Period
A unit of the geological time scale that is a subdivision
of a period.
Epoch
the informal name for the eons that came before
the current Phanerozoic eon.
Precambrian
– It refers to the earliest interval (eon) of Earth history—
before the oldest known rocks.
Hadean
The organization that is largely responsible for maintaining and updating the geologic time scale
International Commission on Stratigraphy
refers to the habitable zone around a star where the
temperature is just right - not too hot and not too cold - for liquid water to exist on an planet.
Goldilocks Zone
“just right” condition to support higher life-forms.
Goldilocks Scenario
A cataclysmic explosion that created all matter and space
Big Bang Theory
13.7
______ contracted and cooled and condensed into dust sized particles that accreted into protoplanets
Solar Nebula Theory
The giant-impact impact suggests that the
Moon formed out of the debris left over from a
collision between Earth and an astronomical
body the size of Mars.
Big Splash
or
Theia Hypothesis
(4.5 Ga)
process of separating out different constituents of a planetary body as a consequence of their physical or chemical behavior, where the body develops into compositionally distinct layers
Planetary Differentiation
- Release of gases that are trapped in Earth’s interior. Comes from the hundreds of active volcanoes worldwide
Outgassing
4.4 Ga
The oldest minerals so far dated on Earth.
- Originally formed by crystallization from a magma
or in metamorphic rocks
Zircon
from Jack Hills, Western Australia
(4.404 Ga)
Type of carbonaceous chondrites that contain
a high proportion of water (up to 22%), and organic
matter in the form of amino acids
C1 Chondrites
4.4 Ga
oldest preserved continental rocks.
- occur as small, highly deformed terranes, which
are incorporated within somewhat younger block of
continental crust .
Acasta Gneiss
from Slave Province of Canada
(4 Ga)
single celled life forms, they send the first free oxygen molecule into our atmosphere.
- earliest bacteria that produces oxygen as a by-product of photosynthesis.
- most diversified group of microorganisms on earth.
Cyanobacteria
3.9 Ga
• Are a distinctive type of rock often found in
(Precambrian) sedimentary rocks.
• They consist of repeated thin layers of iron
oxides, either magnetite (Fe3O4) or hematite
(Fe2O3), alternating with bands of ironpoor shale and chert.
Banded Iron Formation
or
BIF
(3.5 Ga)
First theorized supercontinent.
Vaalbara
3.5 - 2.5 Ga
Vaalbara is composed of two cratons named
Kaapval Craton - Africa
Pilbara - Australia
Organic microfossils that played a role in increasing
the amount of oxygen in the oceans during the
Neoproterozoic era, which eventually paved the way
for the rise of animals and other large and complex
organisms
Acritarch
3.2 - 1.4 Ga
oldest confirmed continent in earth history.
- Half a billion years younger than Vaalbara.
Ur
- formed as a result of a series of accretion events and
the formation of new continental crust. - Swarms of volcanic dikes and their paleomagnetic
orientation as well as the existence of similar stratigraphic sequences permit this reconstruction
Kenorland
2.7 Ga
preserved as corkscrew-shaped or spaghetti
like marks that look like a random combination of
O’s C’s and 6’s.
Grypania
Oldest Megafossil in Michigan
(2.1 Ga)
The oldest impact crater on Earth is also the largest (300 km diameter)
Vredefort Crater
- South Africa
2. 02 Ga
2nd largest impact crater
250km diameter
Sudbury Crater
1.85 Ga
The oldest impact crater on Earth is also
the largest
Rodinia
1.3 - 1.1 Ga
• oldest known sexually reproducing organism and the oldest multicellular organism that used photosynthesis
Bangiomorpha
1.2 Ga
meaning all southern land
also known as Gondwanaland and Vendian Supercontinent
Pannotia
Oldest animals fossils so far discovered (600 Ma)
Ediacaran Fauna
First appearance of Trilobites , jawless fishes (ostracoderms) , forams, octopus, molluscs, archeocyatids, brachiopods, gastropods, ostracods, conodonts and graptolites.
• Archeocyatids
Cambrian
Six Paleozoic continent form from the break-up of of Pannotia
- GONDWANA
- S. America, Africa, Florida, AQ, AU, IN - LAURENTIA
- N. America, GL, Scotland. E. RU - BALTICA
- RU, PL, N. DE, Scandinavia - SIBERIA
- RU, IN
5.KAZAKHSTANIA
- CHINA
- All of SE Asia, Indochina, TH, MY
First of appearance of 1. Nautilods 2. Fungi appeared on land 3. Moss – first non vascular plant 4. Eurypterids – sea scorpions • Abundances of Cephalopods and Acritarchs
Ordovician
2nd largest mass extinction
85 % casualty on all marine and land species
• 60 % marine invertebrates died
Ordovician-Silurian Mass Extinction
• First appearance of;
- Acanthodian - First jawed fishes
- Cooksonia – first vascular plant
- First freshwater fish
- First coral reef
Silurian
Age of Fishes and Orogeny • First appearance of; 1. Wingless insects 2. Ammonites 3. Amphibians 4. Sharks
Devonian
Oldest known amphibians
Ichthyostega
Orogenies that affected the Appalachian Mobile belt
- Taconic
- Caledonian
- Acadian
5th largest mass extinction
• 80% of all living species, primarily the marine community have been wiped out.
• Extinction of cooksonia, tribulate corals, stromatoporoids, ostracoderms and
placoderms.
Late Devonian Mass Extinction
First appearance of Lycopsids , Conifers,
Cycads and first forest
Carboniferous
oldest known reptile located in Scotland
Weslothiana
are the major source of the worlds coal, coal result from the alteration of plant remains accumulating in low, swampy area
Pennsylvanian Rocks
It is named after the tillite found in the region of South Africa , where evidence for this ice age was first clearly
identified in the 19th century.
Karoo Glaciation
it means all earth
Pangea
Sea surrounding Pangea
Panthalassa
Largest mass extinction and lso known as the “Great Dying”
• Elimination of over 95 % marine and 70% terrestrial species
• Extinction of trilobites, eurypterids, acanthodians and blastoids
• Causes;
1. bolide impact events
2. Increase volcanism
3. Sudden release of methane from seafloor
4. Sea level change
5. Increase anoxia
6. Increase aridity
7. Preadation and competition
Permian-Triassic Mass Extinction
First appearance of ;
- Frogs, turtle, snakes
- Archosaurs – proto dinosaurs
- Mammals ( family of rodens)
- Pleorsuars
- Cocoliths
- Sea urchins
Triassic
Break up of Pangea into land mass
- Gondwana (S. America, Africa, IN, AQ, AU)
2. Laurasia (N. America, Eurasia
It was caused by the collision of a volcaninc arc with
western North America
Sonoma Orogeny
Marine genera observed extinction: 53% • Marine species extinct 80% • Extinction of conodonts • Causes ; 1. climate change 2. Rising sea levels resulting from the sudden release of large amounts of carbon dioxide.
Triassic-Jurassic Mass Extinction
• First appearances;
- Planktonic forams
- Archaeopteryx – first birds
Jurassic
a newly discovered bird-like dinosaur is about 10 million
years older than Archaeopteryx,
Aurornis Xui
First appearances of 1. Marsupials 2. Diatoms 3. Angiosperms 4. Crocodiles appeared ( 110 Ma) • Ammonites found in Catanduanes
Cretaceous
76% of all species lost • Extinction of dinosaurs and ammonites • Causes by a Meteorite impact ( presence of iridium layer ) • Form Chicxulub crater – 150 km across in Mexico
K-T Mass Extinction
Early Primates
Australopithecus (3 - 1.4 Ma)
• Homo habilis (2.4 to 1.5 Ma)
• Homo erectus ( 1.9 Ma )
• Homo sapiens (400,000 - 150,000 years ago)
• Neandertal (90,000 to 30,000 years ago)
• Homo floresiensis (18,000 years ago.)
First appearance
- horse
- bats
- whales
- elephants
- penguins
Eocene
The second greatest volcanism of the Cenozoic Era
La Garita
• First appearance of 1. Dog 2. Antelop 3. Bear 4. Giraffe 5. Deer 6. Megalodons 7. Raccoons • Forest give way to grassland
Miocene
elephant-like bones that had been found in Europe
Elephas Primigenius
renamed to
Mammathus Primigenius
