ter> The Fundamental Principles of Relative Dating Relative dating involves placing events in their proper chronological sequence, that is, in the order of their occurrence (Dutch 1998). This type of dating tells us which geologic event happened first, but does not give an exact date to which something happened. There are several different methods that are used in relative dating. These are the fundamental methods that are used in the field by geologists’ and earth scientists to gather information about the relative age of rock bodies and other cool geologic stuff. These principles are the principle .
Name: _________________________ Geologic Principles and Relative Dating 1. How old is the Earth? a. ________________________________________________________ b. Much of its history is recorded in the rock. c. Observations of fossils, rock types, evidence of faulting, uplifts and folding as well as __________________________________________ ________________________________________________________ 2. Relative Dating a. ________________________________________________________ to the ages of other rock or events in the geological sequence b.
Saying “ ________________________________________________” shows its age relative to a known. c. This means that geologists can say which layers are older than which and thus ________________________________________________ 3. Principle of Uniformitarianism a. This geologic Principle states that all geological processes ( ________ _______________________________________________________) that occur today also occurred in the past in the same way.
b. ________________________________________________________ 4. Time is the rate at which things change. The history of the Earth is explained as on order of events. There are 2 ways of dating these events in geology. a. The first manner of depicting the order of geologic events is called _______________________________.
In this technique events are simply younger or older than some other event. _________________ ____________________________________________. For example: The rocks in Bryce Canyon were deposited before the canyon formed. 5. The basic Principles are: a.
The Law of Superposition -________________________________ _______________________________________________________. Name: _________________________ b. The Law of Original Horizontality -___________________________ ________________________________________________________ ____________________________. c. The Law of Cross Cutting Relationships -____________________ _______________________________________________________. d. The Law of Inclusions -___________________________________ _______________________________________________________.
e. These are the fundamental principles geologists use in determining the sequence of events and relative ages of layers that are found in the rock record. Following are examples of each.
6. Law of Superposition 7. _____________________________________________________________ _____________________________________________________________ 8.
Law of Original Horizontality Name: _________________________ 9. ______________________________________________________________ 10. Law of Cross Butting Relations a. This red area represents an igneous intrusion. It is younger than the sedimentary rock that it cuts across 11. Features within the rock layers a. Igneous Intrusion ________________________________________________________ ________________________________________________________ 12.
Law of Cross Cutting Relations Name: _________________________ 13. Law of Cross Cutting Relations a. Faulting is another example of cross cutting relation.
The fault in younger than all of the layers it cuts across 14. Law of inclusions 15. a. The red line is _______________________________________________________ ___________________________________________________________________ ___________________________________________________________________ Name: _________________________ 16.
There are 3 main types of Unconformities: a. Disconformity – The layers above and below the erosional surface are parallel. They could be horizontal or tilted. b. Angular Unconformity – tilted rocks are eroded and a new set of sediment are laid down on top of them. c. Nonconformities – Sediment layers set on top of and around an intrusion of igneous rock that has been eroded. 17. Disturbed Rock Layers a. Folding – Occurs when ________________________________________ ___________________________________________________________ i.
Often causes Mountains Name: _________________________ b. Faulting – A fault is __________________________________________ ___________________________________________________________ c. Tilting – Occurs when _________________________________________ ___________________________________________________________ 18.
Index Fossils – Used to determine the age of the rock the fossil is found in if the fossil meets the two conditions a. __________________________________________________________ b.
__________________________________________________________ 19. Geologic Columns a. Geologists take core samples from the Earth’s Crust all over the world b. They take __________________________________________________ __________________________________________________________ c.
They match up layers based on _________________________________ ___________________________________________________________ d. Sometimes layers are missing from one column because of an unconformity, so geologists ____________________________________ ___________________________________________________________ ___________________________________________________________ 20.
Core Samples 21. Core Samples Put together
best relative dating principles diagram - Key Principles of Relative Dating Flashcards
The through stratigraphy of the area of southeastern is a great example of Original Horizontality and the Law of Superposition, two important ideas used in relative dating. These strata make up much of the famous prominent rock formations in widely spaced protected areas such as and . From top to bottom: Rounded tan domes of the , layered red , cliff-forming, vertically jointed, red , slope-forming, purplish , layered, lighter-red , and white, layered sandstone.
Photo from , Utah. Relative dating is the science of determining the relative order of past events (i.e., the age of an object in comparison to another), without necessarily determining their , (i.e. estimated age). In geology, or , and can be used to correlate one with another. Prior to the discovery of in the early 20th century, which provided a means of , and used relative dating to of materials.
Though relative dating can only determine the sequential order in which a series of events occurred, not when they occurred, it remains a useful technique. Relative dating by is the preferred method in and is, in some respects, more accurate. The , which states that older layers will be deeper in a site than more recent layers, was the summary outcome of 'relative dating' as observed in geology from the 17th century to the early 20th century.
The regular order of the occurrence of fossils in rock layers was discovered around 1800 by . While digging the in southwest England, he found that fossils were always in the same order in the rock layers.
As he continued his job as a , he found the same patterns across England. He also found that certain animals were in only certain layers and that they were in the same layers all across England.
Due to that discovery, Smith was able to recognize the order that the rocks were formed. Sixteen years after his discovery, he published a of England showing the rocks of different eras. Principles of relative dating Methods for relative dating were developed when geology first emerged as a in the 18th century. Geologists still use the following principles today as a means to provide information about geologic history and the timing of geologic events.
Uniformitarianism The states that the geologic processes observed in operation that modify the Earth's crust at present have worked in much the same way over geologic time.
A fundamental principle of geology advanced by the 18th century Scottish physician and geologist , is that "the present is the key to the past." In Hutton's words: "the past history of our globe must be explained by what can be seen to be happening now." Intrusive relationships The principle of relationships concerns crosscutting intrusions.
In geology, when an intrusion cuts across a formation of , it can be determined that the igneous intrusion is younger than the sedimentary rock. There are a number of different types of intrusions, including stocks, , , and . Cross-cutting relationships can be used to determine the relative ages of and other geological structures. Explanations: A – rock strata cut by a ; B – large (cutting through A); C – (cutting off A & B) on which rock strata were deposited; D – (cutting through A, B & C); E – even younger rock strata (overlying C & D); F – (cutting through A, B, C & E).
The pertains to the formation of and the age of the sequences through which they cut. Faults are younger than the rocks they cut; accordingly, if a fault is found that penetrates some formations but not those on top of it, then the formations that were cut are older than the fault, and the ones that are not cut must be younger than the fault. Finding the key bed in these situations may help determine whether the fault is a or a . Inclusions and components The explains that, with sedimentary rocks, if inclusions (or ) are found in a formation, then the inclusions must be older than the formation that contains them.
For example, in sedimentary rocks, it is common for gravel from an older formation to be ripped up and included in a newer layer. A similar situation with igneous rocks occurs when are found. These foreign bodies are picked up as or lava flows, and are incorporated, later to cool in the matrix. As a result, xenoliths are older than the rock which contains them. Original horizontality The states that the deposition of sediments occurs as essentially horizontal beds.
Observation of modern marine and non-marine sediments in a wide variety of environments supports this generalization (although is inclined, the overall orientation of cross-bedded units is horizontal). Superposition The states that a sedimentary rock layer in a tectonically undisturbed sequence is younger than the one beneath it and older than the one above it.
This is because it is not possible for a younger layer to slip beneath a layer previously deposited. The only disturbance that the layers experience is bioturbation, in which animals and/or plants move things in the layers. however, this process is not enough to allow the layers to change their positions.
This principle allows sedimentary layers to be viewed as a form of vertical time line, a partial or complete record of the time elapsed from deposition of the lowest layer to deposition of the highest bed. Faunal succession The is based on the appearance of fossils in sedimentary rocks.
As organisms exist at the same time period throughout the world, their presence or (sometimes) absence may be used to provide a relative age of the formations in which they are found. Based on principles laid out by William Smith almost a hundred years before the publication of 's , the principles of succession were developed independently of evolutionary thought. The principle becomes quite complex, however, given the uncertainties of fossilization, the localization of fossil types due to lateral changes in habitat ( change in sedimentary strata), and that not all fossils may be found globally at the same time.
Lateral continuity Schematic representation of the principle of lateral continuity The states that layers of initially extend laterally in all directions; in other words, they are laterally continuous. As a result, rocks that are otherwise similar, but are now separated by a or other feature, can be assumed to be originally continuous. Layers of sediment do not extend indefinitely; rather, the limits can be recognized and are controlled by the amount and type of sediment available and the size and shape of the .
Sediment will continue to be to an area and it will eventually be . However, the layer of that material will become thinner as the amount of material lessens away from the source. Often, coarser-grained material can no longer be transported to an area because the transporting medium has insufficient energy to carry it to that location. In its place, the particles that settle from the transporting medium will be finer-grained, and there will be a lateral transition from coarser- to finer-grained material.
The lateral variation in sediment within a is known as . If sufficient sedimentary material is available, it will be deposited up to the limits of the sedimentary basin. Often, the sedimentary basin is within rocks that are very different from the sediments that are being deposited, in which the lateral limits of the sedimentary layer will be marked by an abrupt change in rock type.
Inclusions of igneous rocks Multiple melt inclusions in an olivine crystal. Individual inclusions are oval or round in shape and consist of clear glass, together with a small round vapor bubble and in some cases a small square spinel crystal. The black arrow points to one good example, but there are several others. The occurrence of multiple inclusions within a single crystal is relatively common are small parcels or "blobs" of molten rock that are trapped within crystals that grow in the that form .
In many respects they are analogous to . Melt inclusions are generally small – most are less than 100 across (a micrometre is one thousandth of a millimeter, or about 0.00004 inches). Nevertheless, they can provide an abundance of useful information.
Using microscopic observations and a range of chemical techniques and can obtain a range of useful information from melt inclusions. Two of the most common uses of melt inclusions are to study the compositions of magmas present early in the history of specific magma systems. This is because inclusions can act like "fossils" – trapping and preserving these early melts before they are modified by later igneous processes.
In addition, because they are trapped at high pressures many melt inclusions also provide important information about the contents of volatile elements (such as H 2O, CO 2, S and Cl) that drive explosive . (1858) was the first to document microscopic melt inclusions in crystals.
The study of melt inclusions has been driven more recently by the development of sophisticated chemical analysis techniques. Scientists from the former Soviet Union lead the study of melt inclusions in the decades after (Sobolev and Kostyuk, 1975), and developed methods for heating melt inclusions under a microscope, so changes could be directly observed.
Although they are small, melt inclusions may contain a number of different constituents, including glass (which represents magma that has been quenched by rapid cooling), small crystals and a separate vapour-rich bubble. They occur in most of the crystals found in igneous rocks and are common in the minerals , , and .
The formation of melt inclusions appears to be a normal part of the crystallization of minerals within magmas, and they can be found in both and rocks. Included fragments The is a method of relative dating in . Essentially, this law states that in a rock are older than the rock itself. One example of this is a , which is a fragment of that fell into passing as a result of . Another example is a , which is a that has been eroded from an older and redeposited into a younger one.
This is a restatement of 's original principle of inclusions and components from his 1830 to 1833 multi-volume , which states that, with , if (or clasts) are found in a , then the inclusions must be older than the formation that contains them. For example, in sedimentary rocks, it is common for from an older formation to be ripped up and included in a newer layer. A similar situation with occurs when xenoliths are found. These foreign bodies are picked up as or , and are incorporated, later to cool in the .
As a result, xenoliths are older than the rock which contains them... Planetology Main article: Relative dating is used to determine the order of events on other than Earth; for decades, have used it to decipher the development of bodies in the , particularly in the vast majority of cases for which we have no surface samples.
Many of the same principles are applied. For example, if a valley is formed inside an , the valley must be younger than the crater. Craters are very useful in relative dating; as a general rule, the younger a planetary surface is, the fewer craters it has.
If long-term cratering rates are known to enough precision, crude absolute dates can be applied based on craters alone; however, cratering rates outside the Earth-Moon system are poorly known. • Stanley, Steven M. (1999). Earth System History. New York: W.H. Freeman and Company. pp. 167–169. . • Reijer Hooykaas, , Leiden: , 1963.
• Levin, Harold L. (2010). The earth through time (9th ed.). Hoboken, N.J.: J. Wiley. p. 18. . • ^ Olsen, Paul E. (2001). . Dinosaurs and the History of Life. Columbia University . Retrieved 2009-03-14. • As recounted in , (New York: HarperCollins, 2001), pp. 59–91. • See 2011-05-14 at the . retrieved May 8, 2011 • D. Armstrong, F. Mugglestone, R. Richards and F. Stratton, OCR AS and A2 Geology, Pearson Education Limited, 2008, p.
276 • Hartmann, William K. (1999). Moons & Planets (4th edition). Belmont: Wadsworth Publishing Company. p. 258. .
ter> The Fundamental Principles of Relative Dating Relative dating involves placing events in their proper chronological sequence, that is, in the order of their occurrence (Dutch 1998). This type of dating tells us which geologic event happened first, but does not give an exact date to which something happened. There are several different methods that are used in relative dating.
These are the fundamental methods that are used in the field by geologists’ and earth scientists to gather information about the relative age of rock bodies and other cool geologic stuff. These principles are the principle of superposition, the principle of original horizontality, the principle of cross-cutting relationships, and the principle of inclusions.
The principle of superposition is defined as in the environment of an undisturbed layer of sedimentary rocks; the layers on the bottom are older than the layers towards the top. The pictures I have taken show very good examples of this. By using the principle of superposition we can know that the layers toward the bottom are older than the layers toward the top.
The rock body shown in the pictures attached, started out as one layer, as millions and millions of years passed more layers of sedimentary rock were placed on top of each other one after another, each layer was deposited at a later time than the one before it. The youngest layer is on the top, and the oldest layer is on the bottom.
This principle was founded by the Danish anatomist Nicolas Steno, who noted that during floods, streams spread across their floodplains and deposit layers of sediment that bury organisms dwelling there. He noticed that later floods produce younger layers of sediments that are deposited or superposed over previous deposits (Dutch 1998). 3 pages, 1387 words ... withstood the test of time.Allan Cox was interested in dating rock specimen and together with Richard Doell and Brent Dalrymple made ...
seismic station. It can move through solid rock and fluids, like water or the liquid layers of the earth. It pushes and ...
steep-sided, symmetrical cones of large dimension built of alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs and ... This is just one example how superposition can occur on a smaller scale. The principle of superposition can also help give a of any type of biological remnants that are contained in the layers.
The next principle that I am going to discuss is the principle of original horizontality. This principle states that rocks are originally layered in horizontal planes, and any inclining area is caused by tilting of the rocks. Steno came up with this principle also (Dutch 1998). In picture number one it is fairly noticeable that the rock layers are higher on the left side than on the right.
This tells us that during some period of time, the rocks were tilted by a geological event. The next method of relative dating that I will discuss is the principle of cross-cutting relationships. This method states that a fracture or an igneous intrusion such as a dike must be younger than the rocks it cuts or intrudes (Dutch 1998).
For example, if hot wax was poured on an ice cube the path that the wax cut across, and probably eroded away, is younger than the original ice. The last principle that I am going describe is the principle of inclusions. The principle of inclusions holds that inclusions or fragments of one rock contained within another are older than the containing the inclusions (Dutch 1998).
For example, a granite batholith, containing pieces of an adjacent sandstone must have been intruded into the sandstone and is thus younger than the sandstone (Dutch 1998). All of the principles that I have discussed above are main fundamental processes of relative dating.
Relative dating gives us a key of how things formed and in what order. It provides us with a basic knowledge a how to date events in chronological order. Most people probably already knew most of these principles, but didn’t know how to relate them to the earth. Relative dating doesn’t directly affect the biosphere, but the processes that it reveals to us, does.
For example, using the principle of original horizontality we know that rocks are layered in horizontal planes.
1 page, 362 words ... these layers. If the rock is layered, then it could have been a part of ... left by this separation makes you suspect that the rock itself is layered, although you cannot see any borders that would distinguish ... think that this rock is sedimentary is its layered structure.
As it is known, sedimentary rocks are formed from numerous layers of sediments, ... So when we see rocks that are tilted we know that a large-scale geological event took place to change the orientation of those rocks. By using this method we can predict how biological organisms were affected by it. Works Cited Dutch, S.I., Monroe, J.S., and Moran, J.M.
(1998) Earth Science. West Wadsworth Publishing, Inc., Belmont, Ca, pp. 239-242.
Laws of Relative Rock Dating