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The Basics of Geology
Transcript of The Basics of Geology
The Basics on the Geological Time Scale
The time scale on the left, shows the different types of eons, eras, and periods of the earth's cycle of life, some of which are present today, wile the others are from the past. The geological time scale isn't the exact times, days, and years because we don't have good equipment to search and find the exact facts of when the earth started to form. But instead estimates on what it would look like.
Here is a 4 minute and 23 seconds music video on the geological time scale.
Geological Time has many topics of facts to know, before people go into a science field of work. Relative Age Dating, Absolute Age Dating, Sources of Error in Radiometric Dating, Fossils, Evolution, and the Geological Time Scale. In addition, the topics are all based on Earth Science and Geology.
is a pair of thin layers of clay and silt of contrasting color and texture that represent the deposit of a single year (summer and winter) in a lake. Such layers can be used to determine the chronology of glacial sediments.
Relative Age Dating
Relative Age Dating puts geologic events in order by considering the principles of; Faunal succession, Uniformitarianism, Original horizontally, Cross-cutting relations, Correlation, Superposition, and Unconformity.
Faunal succession has no life form that is exactly duplicated at another point in time.
Uniformitarianism is about "The present is the key to the past."
Original horizontality have sediments that are deposited in flat-laying layers.
Cross-cutting relations are faults or dike that cuts across layers are younger than the layers.
Correlation are two rocks containing the same fossils that are the same age.
Superposition, if undisturbed, the oldest is on the bottom, the youngest is at the top of the soil.
Fragments are pieces of rock, xenoliths or intraclasts, inside a rock, which is older than the actual rock on the outside.
Unconformity is a break in the rock record due to erosion or non-deposition. Angular un-conformity layers are above and below, but not parallel. And Disconformity layers are above, below and are parallel.
Here is a short video on Relating Age Dating. Please don't mind the song in this video. I am sorry beforehand if I hurt anyone's feelings about religion, because the song has nothing to do with God in science.
Absolute Age Dating
Absolute Age Dating finds a numerical age for a rock by radiometric dating techniques, counting tree rings,
, or using index fossils. Also Absolute Age Dating talks about Radiometric Dating and when an igneous rock forms it can obtain a parent isotope.
Radiometric Dating: Half-life - the length of time for half a radioactive parent sample to decay and become a stable daughter. It is unique for each radioactive isotope. It never changes.
Isotope instantaneously starts to spontaneously decay, to form daughter isotopes. Scientists (Geochronologists) can measure the amount of parent and daughter isotopes in a rock sample by using a
. Also Geochronologists can determine how many half-lives has passed. The age of the sample is calculated by using this method: Age = (# of half-lives) X (length of half-life)
Sources of Error in Geometric Dating
Daughter isotopes may have been present when the rock was viewed, to make the rock look older in age. Also the daughter isotopes may have escaped from the rock, the argon gases, to make the rock look younger in age. Some parent/daughter isotopes may have been added to a sample, to make the sample look younger or older, respectfully. Scientists can correct possible errors by adding more than one radiometric isotope and comparing the ages obtained. Numerically age ranges from sedimentary rock that can be obtained by radiometric dating sills, dikes, or lava flows that overlie, underlie, or intrude the isotopes. Carbon 14 has a short half-life (5730 years) and is predominantly used to date organic material.
is an apparatus for separating isotopes, molecules, and molecular fragments according to mass. The sample is vaporized and ionized, and the ions are accelerated in an electric field and deflected by a magnetic field into a curved trajectory that gives a distinctive mass spectrum.
A fossil is a replica of an organism that the hard parts of the fossil is preserved most easily. Which generally fossilized under water where most sediment's accumulated. Fossils have many topics to cover, to understand the meaning of fossilization of fossils. For example; Rapid burial, Fossilization, a Trace Fossil, Per-mineralization, Original preservation, Carbonization, Replacement, Mold, an Index Fossil, and Cast.
Rapid Burial is required to prevent scavenging and decay (i.e. seal from oxygen and bacteria.
Fossilization of soft parts, (a replica, not the soft parts themselves), requires the entire organism to be buried shortly after death in deep, low-oxygenated water.
A trace fossil is a sedimentary structure made by an organism such as a footprint, burrow, or
is a waste matter discharged from the bowels after food that has been digested; excrement.
Methods of Fossilization
Original Preservation is a original skeletal material or soft tissues remain e.g. frozen wooly mammoth.
Carbonization is a "picture" in carbon; common fossilization method.
Replacement is a mineral, (i.e. quartz), that takes place of the original structure.
Per-mineralization is a mineral fills in pore spaces of the original structure.
Mold are sediments that solidify around the shell, water flowing through dissolves of the shell and hollow remaining shows the external features of the shells.
Cast are sediments that fill in the mold and show the external features of the shell, not internal structures of the present.
An index fossil is one that is especially useful in correlating strata. It may be a plant or a animal that was short-lived, geographically wide spread, abundant, and is easily identified.
Punctuated equilibrium is a model for a evolution that predicts that life forms remain unchanged for long periods of time. Then suddenly, undergo a major change by a long period of stability.
Adaptive equilibrium are animals that adapt to the environment they are in and consequently are different from the periods of time. Then suddenly, undergo a major change followed by a long period of stability.
Natural selection is a principle of theory of evolution: survival of the fittest.