clues to earth’s past
DESCRIPTION
Clues to Earth’s Past. Fossils. Remains, imprints, or traces of prehistoric organism. Permineralized remains. Fossils where the spaces inside are filled with minerals. Carbon Film. A flim of carbon can form around an organism creating a silhouette. Mold-Cast. - PowerPoint PPT PresentationTRANSCRIPT
Clues to Earth’s Past
Remains, imprints, or traces of prehistoric organism.
Fossils
Fossils where the spaces inside are filled with minerals
Permineralized remains
A flim of carbon can form around an organism creating a silhouette
Carbon Film
Mold- imprint left after hard parts of organism decay
Cast- a copy of organism made from the mold
Mold-Cast
Fossils that are evidence of organisms activity (not organism itself)
Such as:Tracks/footprintsBurrowsTrails
Trace Fossils
Abundant, widespread organisms that existed for a SHORT period of time.
Index Fossils
In undisturbed layers of rock, the oldest rocks are found at the bottom, with the rocks becoming younger towards the top.
Principle of Superposition
Relative age is how old a rock or fossil is in COMPARISON to the ages of other things.
Relative Age
when an igneous intrusion cuts across a formation of rock, it can be determined that the igneous intrusion is younger than the rock it’s cutting through.
Igneous Intrusion
Unconformities are when layers of rock are missing
Unconformities develop when running water or glaciers remove rock layers
Unconformities
When rock layers are tilted and younger sediment layers are deposited horizontally on top of the eroded and tilted layers
Angular
When a layer of horizontal rock is exposed and eroded before younger rocks form over it
Disconformity
When sedimentary rock forms over eroded metamorphic or igneous rock
Nonconformity
The same rock layers can be found in different locations; FOSSILS must be used to prove that the layers match up
When the layers are too disturbed:
Calculating the absolute age of a rock by measuring the amounts of materials in a rock and knowing the material’s half life.
Absolute Dating
Half-Life: Time it takes for half of the atoms
in an isotope to decay
Breaking down of an atom into a proton and an electron.
Radioactive Decay
Uses the properties of atoms in rocks and other object to determine their ages.
Radiometric Dating
Principle that Earth’s processes occurring today are similar to those that occurred in the past.
Uniformitarianism