final Flashcards
3 kinds of fossils
body, trace, chemical
stress
the amount of force per unit area
confining stress
stress is equal in all the three directions of the space for a certain point in the Earth’s crust;
differential stress
occurs in the case of crustal movements; stress is higher in certain directions
differential stress (compression)
stress pushes on rock
differential stress (tension)
stress stretches the rock
differential stress (shear)
stress is applied in two opposite directions
folds
result of ductile deformation
faults
result of brittle deformation
anticline classifications
upright, inclined, overturned, recumbent
strike-dip faults
displacement is horizontal
drip-slip faults
vertical displacement
oblique-slip faults
horizontal and vertical displacement
normal faults
downward displacement
reverse faults
upward displacement
thrust faults
reverse faults, dip at low angle
body fossils
direct or altered remains of ancient organisms (teeth, shells, etc)
trace fossils (ichnofossils)
evidence of the activity of ancient organisms
recrystallization
This process involves the conversion of the original minerals of the test into a different mineral.
what is the most common transformation in recrystallization?
aragonite to calcite
aragonite and calcite are…
both carbonates but have different crystal structures
what changes in recrystallization
mineralogical composition; chemical composition stays the same
moldic preservation
The original test or shell is dissolves
- the shape of the former organism is given by the lithified sediment infill.
replacement
particular case of moldic preservation
the space from the dissolution of the original test is filled by a new mineral.
pyritization
most frequent case of replacement
permineralization
Permineralization results from the filling of the pore spaces usually by opal or chalcedony
carbonization
Occurs when the fossils are buried deep into the Earth’s crust and all the organic material is expelled, excepting for the carbon.
characteristics of carbonization
fossilization that is often in plants, algae, and fish
these fossils have a black appearance
congealment
This kind of fossilization occurs at high latitudes, where there is a thick layer of frozen soil and rock at the uppermost part of the Earth’s crust.
fossilization in amber
best preserved, organic resin to preserve bodies
fossilization in tar pits
occurs in zones with oil and viscous fluids (California)
stenos principles - principle of layer superposition
In any sequence of undisturbed layers, the older layer is at the bottom of the succession and the younger layers occupy a progressively higher position
stenos principles - principle of successive layer formation
At the time of formation of a layer only fluid was above it. Accordingly, none of the above existing layers in the stratigraphical succession existed at that time.
stenos principles - principle of original layer horizontality
he stated that originally, the layers should have been horizontal. Accordingly, the steeply inclined layers can be regarded as indicative for an episode of crustal disturbance.
stenos principles - principle of lateral layer continuity
layers are laterally continuous
1774 Georges louis leclerc
first calculation of earths age
- ended the influence of creationist ideas in science
mud cracks
Mud-cracks are sedimentary structures that form frequently at the surface of the Earth, in the fine sediments that are exposed to the atmospheric conditions during the arid periods.
borrowings
produced by those organisms that develop their life cycles buried in sediments, as adaptations to avoid the predators in the open waters, or for feeding purposes.
Steno refined this principle by admitting that at the time of deposition, layers could reflect the irregularities at the basin floor.
Principle of original layer horizontality
conformable succession
strata without depositional breaks
non-conformable succession
strata are separated by surfaces of discontinuity encompassing substantial amounts of geological time (unconformities)
disconformity
a surface of erosion between younger and older beds parallel with one another.
angular unconformity
erosional surface on tilted or folded strata over which younger strata have been deposited.
nonconformity
erosion surface that cuts into metamorphic or igneous rocks is covered by sedimentary rocks.
principle of inclusion (igneous)
states that the inclusions within an igneous rock are older than the rock that includes them
An inclusion in igneous rocks also is known as
xenolith
principle of cross cutting (igneous)
states that a cross-cutting rock is younger than the cross-cut one
what are the four eons
PHANEROZOIC
PROTEROZIC
ARCHEAN
HADEAN
PHANEROZOIC
visible life forms
PROTEROZIC
early life forms
ARCHEAN
oldest rocks
HADEAN
no rock record
radioactive decay
Some of the isotopes are stable, other not. An unstable isotope nucleus can be transformed spontaneously into an isotope with a stable nucleus configuration.
half-life
time it takes for one half of the atoms of the original unstable parent element to decay to atoms of a new and more stable daughter element.
the dominant elements in the life forms today (CHON)
carbon hydrogen oxygen nitrogen (sulfur and phosphorous are also present)
what was the starting point of oparins model
the fact that the plant cells are too complex to have been formed without a long process of inorganic evolution.
Alexandr Ivanovic Oparin (1896-1980) postulated that it is possible that CHON molecules could have been formed before life begun to give rise to the first cells.
Oparin model showed
the Earth’s original atmosphere was a reducing one, without much free molecular oxygen.
CHON molecules could be accumulated in a ____ atmosphere.
reducing (this is early in the atmosphere age)
primordial soup
simple organic molecules could have accumulated at the earths surface and dissolved in water
this group contains some of the oldest sedimentary rocks on earth
the Greenland isua supercrustal group
isua supercrustal group
rare oxides and carbonates that do not form layers
- graphite levels indicate organic origin
Miller and Urey experiment (1953) demonstrated …
monomers can be combined to form organic molecules
polymerization
Combining the simple CHON molecules into larger molecules would result in the formation of polymers, a necessary step in the development of the life forms on Earth.
example of polymerization
Cellulose (carbohydrate polymer)
_____ do not fossilize
molecules
______ is a lithological unit in a volcano-sedimentary formation.
apex chart
Earliest bacteria and cyanobacteria debris
Early Archean of western Australia (Pilbara Craton).
what did the apex chart show
folded filament with cell like structures made of carbon.
stromatolites
are organo-sedimentary structures of various shapes
Growth surface (stromatolites)
thin layer of oxygen-producing photosynthetic cyanobacteria and aerobic bacteria.
undermat (stromatolites)
thin bacterial layer of non-oxygen-producing photosynthetic bacteria
- are anaerobic, still can use oxygen-when available
oxygen depleted zone (stromatolites)
thicker layer bacteria. populated by anaerobic
stromatolite mass (stromatolite)
includes most of the stromatolite and consists of calcium carbonate;
- there are no living bacteria and cyanobacteria in this portion of the stromatolite.
Banded Iron Formation (BIF)
The rock record around 2.2-1.9 billion years contains rocks rich in iron oxides and hydroxides;
oldest eukaryotes are
biomarkers (2.1, 1.8B yrs)
where were the first isolated true eukaryote cells discovered
cherts of bitter springs formation of central Australia
bitter springs formation
Some of these were caught in the process of cellular division, and are among the very few cases in which even the nucleus was fossilized. In other the offspring cell unique arrangement during the cellular division indicates clearly that the organisms belong to the eukaryote group
cell arrangement of the first eukaryotes suggest
meiotic cell division
examples of eukaryotes
Bangiomorpha
Torridonophycus
melanocyrilium
deep sea drilling project
investigated the sediments and sedimentary rocks in the deepest parts of the ocean
what has the sea drilling project done
Observations have been made on the the sea floor morphology.
Zones of consumption of oceanic crust are regarded as ______
convergent zones
what can occur either between plates consisting of oceanic crust or between plates with different constitution (continental vs. oceanic).
subduction and consumption
subduction is accompanied by …
volcanism, crustal movements resulting in sediment folding and faulting, earthquakes, etc.
wilson cycle
represents the cycle of birth, evolution and close-up of an oceanic basin.
