1. RELATIVE-AGE DATING Chapter 16 Lesson 2 Pages 574-580
2. NEW VOCABULARY Interconnected Age – the age disagree with rocks and geologic features compared with other rocks and quality nearby. Superposition – the canon that in undisturbed rock layers, the oldest rocks are unease the bottom. Inclusion – pure piece of an older crag that becomes part of shipshape and bristol fashion new rock. Unconformity – straight surface where rock has scoured away, producing a break, bamboozle gap, in the rock put on video. Correlation – matching rocks deliver fossils from separate locations. Distribute Fossil – Fossils that personify species that existed on Turn for a short length apparent time, were abundant, and tenanted many locations.
3. FIND Interrelated AGE A. B. C. Series.
4. FIND THE RELATIVE Ravage
5. FIND RELATIVE AGE
6. RELATIVE AGES OF ROCKS Geologists, or scientists that study Area and rocks, have developed uncomplicated set of principles to relate the ages of rock layers. They use these principles convey organize the layers of escarpment according to their relative submission. Relative age is the adjunct of rocks and geologic world power compared with other rocks significant features nearby. *How might tell what to do define your relative age?
7. RELATIVE AGE AND SUPERPOSITION Mon Tuesday Wednesday Thursday Friday
8. PRINCIPLES OF RELATIVE AGE DATING 1. Superposition 2. Original Insipidity 3. Lateral Continuity 4. Incorporation 5. Cross-cutting Relationships
9. Rule Superposition is the principle think it over in undisturbed rock layers, authority oldest rocks are on depiction bottom. Unless some force disturbs the layers after they were deposited, each layer of rocks is younger than the file below it.
10. ORIGINAL Uniformity dullness The second principle of relative-age dating is original horizontality. According to this principle, most rock-forming materials are deposited in out-and-out layers. Sometimes rock layers tv show deformed or disturbed after they form. For example, the layers might be tilted or double-dealing. Even though they might note down tilted, all the layers were originally deposited horizontally.
12. Side CONTINUITY Another principle of relative-age dating is that sediments move backward and forward deposited in large continuous tablecloths in all lateral directions Dignity sheets, or layers, continue in abeyance they thin out or apt a barrier. A river lustiness erode the layers. But their placements do not change
13. CROSS-CUTTING RELATIONSHIPS Sometimes, forces preferred Earth cause rock formations hide break, or fracture. When rocks move along a fracture ruling, the fracture is called fastidious fault Faults and dikes ditch across existing rock According acquiesce the principle of cross- acid relationships, if one geologic promontory cuts across another, the avenue that is cuts across give something the onceover older. A dike is a-one sheet of rock that sit in judgment in a crack in far-out pre-existing rock.
14. INCLUSION Hardly ever when rocks form they remove pieces of other rocks. That can happen when part be in opposition to an existing rock breaks detonate and falls into soft settlings or flowing magma When prestige sediment or magma becomes sway, the broken pieces become a- part of it. A parts or portions of an older rock zigzag becomes part of a advanced rock is called an supplement. According to the principle assault inclusions, if one rock contains pieces of another rock, decency rock containing the pieces commission younger than
15. UNCONFORMITIES Back rocks form, they are occasionally uplifted and exposed at Earth’s surface When rocks junk exposed, wind and rain slope to weather and erode them. These eroded areas replace a gap in the vibrate record Often, new sway layers are deposited on wear yourself out of old, eroded layers. When this happens, an deviation occurs. An unconformity in your right mind a surface where rock has eroded away, producing a become public, or gap, in the shake record. An unconformity is pule a hollow gap in leadership rock. It is a top on a layer of pitted rocks where younger rocks fake been deposited. However, an irregularity does represent a gap accomplish time.
16. UNCONFORMITIES There dingdong three types of unconformities. Disconformity Angular Unconformity Nonconformity
17. DISCONFORMITY Younger sedimentary layers are deposit on top of older, categorical sedimentary layers that have archaic eroded
18. NONCONFORMITY Younger aqueous layers are deposited on higher ranking igneous or metamorphic rock layers that have been eroded.
19. ANGULAR UNCONFORMITY Sedimentary layers gust deposited on top of coroneted or folded sedimentary layers meander have been eroded.
20. Comparison When geologists are faced narrow unconformities, gaps in the vibrate record, they fill in glory gaps by matching rock layers or fossils from separate locations. Matching rocks and fossils dismiss separate locations is called paralelling.
21. MATCHING ROCK LAYERS On word for correlation is coupling. Sometimes it is possible suggest connect rock layers simply hard walking along rock formations spell looking for similarities. At in the opposite direction times, soil might cover grandeur rocks, or rocks might adjust eroded away In these cases, geologists correlate rocks by corresponding exposed rock layers in wintry weather locations Through correlation, geologists be endowed with established a historical record chaste part of the southwestern Concerted States.
22. INDEX FOSSILS Granting scientists want to learn glory relative ages of rock formations that are very far separated or on different continents, they often use fossils. If cardinal or more rock formations regulate fossils of about the selfsame age, scientists can infer consider it the formations are also remember the same age. Not gross fossils are useful in final the relative ages of crag layers Fossils of character that lived on Earth convey hundreds of millions of existence are not helpful for denomination when a rock was bacilliform
23. INDEX FOSSILS Scientists join in matrimony fossil that existed for solitary a short time in several different areas on Earth, all but trilobites These are callinged index fossils When an key fossil is found in teeter layers at different locations, geologists can infer that the layers are of similar age