The Rock and Fossil Record. Uniformitarianism - proposed by James Hutton - states that Earths...
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Transcript of The Rock and Fossil Record. Uniformitarianism - proposed by James Hutton - states that Earths...
The Rock and Fossil Record
Uniformitarianism
• - proposed by James Hutton
• - states that Earths landscape is constantly changing due to the same geologic process that have happened throughout time (weathering, erosion, deposition)
Catastrophism
•- states that all geologic change occurs suddenly due to huge catastrophes
•- Now we know geologic change is a combination of both
Relative Dating
•- to determine if something is older or younger than something else
Superposition
•- young rocks lie above older rocks in an undisturbed sequence
•- however due to disturbances such as folding, tilting, faults, intrusions, not always in a nice horizontal layer
Superposition
Superposition
Superposition
Geologic Column
Folding
Folding
Tilting
Tilting
Faults
Faults
Intrusions
Intrusions
Geologic Column
- Geologists have combined data from all the known undisturbed rock sequences around the world to come up with this
• - it is the ideal sequence of rock layers that contains all the known fossils and rock formations on Earth, use it to interpret rock sequences by comparing it to disturbed rock sequence
Geologic Column
Unconformity
• - gaps in rock layer sequence caused by erosion or nondeposition.
Unconformity
Unconformity
FOSSILS
•- any naturally preserved evidence of life
•- rock fossils, petrifaction, amber fossils, mummification, frozen fossils, fossils in tar.
Rock Fossils
Petrified Wood
Amber Fossils
Mummification
Frozen Fossils
Tar Pit Fossils
Trace Fossils
• – preserved evidence of an animals activity (footprints, coprolites)
Trace Fossils
Coprolites
Mold
• – a cavity where an organism was buried, but decayed
Mold
Cast
– when a mold gets filled in with sediment and becomes a fossil
Cast
Absolute Dating
• – how to establish the actual age of an object.
Radiometric Dating
– by knowing the rate of radioactive decay, you can figure out the age of a rock. (Uranium-lead, potassium-argon, carbon-14)
Radiometric dating
Carbon 14 Dating
Index Fossils
• – if they know when one of the organism lived, can date the layer it was found in to date unknown fossils.
Index Fossils
The Geologic Time Scale
•- divides Earths 4.6 billion year history into distinct time intervals.
•- the divisions are eons, era, periods and epochs.
Geologic Time Scale
Paleozoic Era – “Old Life”
•- started with no land organisms, then came plants, amphibians and insects. At the end came a mass extinction when 90% of all species perished. • •1. Grand Canyon formed•2. Trilobites in sea, land plants •3. Coral reefs, insects and fish
Paleozoic Era
Mesozoic Era : Middle Life”
- the age of reptiles, when dinosaurs existed, birds and small mammals began to evolve.
•- At the end, 50% of the species became extinct, including dinos.
•4. Pterosaurs appear, conifers develop
•5. Reptiles develop
•6. Dinosaurs abundant
Mesozoic Era
Cenozoic Era “ recent life”
•era we live in, the age of mammals, many now extinct
•7. Flowering plants and mammals appear
•8. Rhinos and birds appear
•9. Mammoths and humans appear.
•
Cenozoic Era