Science Earth’s Changing Surface Chapter 4 Section 2.
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Transcript of Science Earth’s Changing Surface Chapter 4 Section 2.
![Page 1: Science Earth’s Changing Surface Chapter 4 Section 2.](https://reader035.fdocuments.net/reader035/viewer/2022072006/56649f425503460f94c6252e/html5/thumbnails/1.jpg)
ScienceEarth’s Changing
SurfaceChapter 4
Section 2
![Page 2: Science Earth’s Changing Surface Chapter 4 Section 2.](https://reader035.fdocuments.net/reader035/viewer/2022072006/56649f425503460f94c6252e/html5/thumbnails/2.jpg)
Finding the Relative Age of Rocks Relative means compared to others The relative age of a rock does not provide
its absolute age The absolute age of a rock is the # of yrs
since the rock formed
![Page 3: Science Earth’s Changing Surface Chapter 4 Section 2.](https://reader035.fdocuments.net/reader035/viewer/2022072006/56649f425503460f94c6252e/html5/thumbnails/3.jpg)
The Position of Rock Layers The Law of Superposition is used to
determine the relative ages of sedimentary rock layers In horizontal sed rock layers, the oldest layer is
@ the bottom Each higher layer is younger than the layers
below it.
![Page 4: Science Earth’s Changing Surface Chapter 4 Section 2.](https://reader035.fdocuments.net/reader035/viewer/2022072006/56649f425503460f94c6252e/html5/thumbnails/4.jpg)
Other Clues to Relative Age Extrusion is lava that hardens on the
surface The rock layers below an e are always older
Intrusion is where the magma cools & hardens into a mass of igneous rock The i is always younger than the rock layers
around or beneath it
A fault is a break in E’s crust
![Page 5: Science Earth’s Changing Surface Chapter 4 Section 2.](https://reader035.fdocuments.net/reader035/viewer/2022072006/56649f425503460f94c6252e/html5/thumbnails/5.jpg)
Gaps in the Geological Record The surface where new rock layers meet a
much older rock surface beneath them is called unconformity This is a gap in the geological record
![Page 6: Science Earth’s Changing Surface Chapter 4 Section 2.](https://reader035.fdocuments.net/reader035/viewer/2022072006/56649f425503460f94c6252e/html5/thumbnails/6.jpg)
Using Fossils to Date Rocks Index fossils help geologists match rock
layers To be useful as an index, a ‘f’ must be
widely distributed & rep a type of org that existed only briefly
I.F. are useful because they tell the relative ages of the rock layers in which they occur