Week 1 Flashcards
Who discovered catastrophism
Bishop James usssher
Based on scripture
How old did ussher believe the earth was
4004 BC
Doctrine of catastrophism
Earths landforms were formed by catastrophic events over short period of time
Occurred due to unknown causes that are no longer present today or
Uniformitarianism
“Present is key to the past”
James Hutton
“Father of geology”
Says the earth is millions of years old
Published the theory of the earth
Who discovered uniformitarianism
James Hutton
Primary dating techniques
Relative: Age of one feature relative to another
Numerical: absolute age, (radiometric dating)
6 relative age dating principles
- Uniformitarianism
- Superposition
- Original horizontality
- Cross cutting relations
- Inclusions
- Fossil succession
Law of superposition
Youngest on top, we build up and don’t shove things in between
Original horizontality
Sedimentary deposits horizontally originally, flat layers first, if it is no longer horizontal, we know an event has happened to move them.
Cross cutting relations
If a rock cuts through another, you know that the one doing the cutting is younger
Principle of inclusions
The youngest includes pieces of the old layers
Principle of fossil succession
Fossils are arranged according to their age and document the evolution of life through time
Fossils are usually found in _____ rocks
Sedimentary- lime/sandstone, marine rocks
Index fossil
Fossils that lived over a short period of time, usually newer, more abundant. The most helpful ones are around for the shortest amount of time
Unconformities
“Gaps in time”. Deformities, we can say it is not in sequential order because something happened.
3 types of unconformities
Angular
Nonconformity
Disconformity
Stratigraphic column
Visual Representation of rock layers
Correlation: tells a longer story
Angular unconformities
Horizontal Young on top, unconformitiy
Tilted older layer on bottom
Nonconformity
Younger, unconformity, igneous/ metamorphic on bottom
Disconformity
Younger, unconformity, older, horizontal, missing info in the middle
We normally only use numerical age dating with ______ rocks
Igneous
Numerical age dating
Measuring radioactive isotopes in a mineral to determine the amount of time elapsed since a minerals formation
Isotope
Variants in the number of neutrons
Half life
The time it takes for half a nuclei in a sample to decay (radioactive disintegration)
Most of the earths history records are from ______ time
Precambrian
Correlation
Correlatting rocks from one place to another
Fossil assemblage
Picture that shows the age ranges of fossil groups
Radioactivity
Nuclei are unstable and they brake apart or decay
Radiometric dating
Reliable means of calculating the age of rocks that contain particular radioactive isotopes
Scientific hypothesis vs inquiry
Inquiry is producing knowledge based on observations/ creating explanations
Hypothesis is explanations/ guesses based on data
