Fossils Flashcards
(42 cards)
What are sedimentary facies?
Bodies of sediment with distinctive physical, chemical, and biological attributes.
What is a marine transgression?
sea level rises relative to the land, causing the shoreline to migrate landward
What happens to facies during marine transgression?
Offshore facies become superposed on nearshore facies
How do rocks age during marine transgression?
Rocks become younger in a landward direction.
What is a marine regression?
sea level falls relative to the continent, causing environments to migrate seaward
What is the vertical sequence of facies during regression?
Nearshore facies overlie offshore facies, and rocks become younger seaward.
Who first recognized Walther’s Law?
Johannes Walther (1860–1937)
What does Walther’s Law state?
Facies in a conformable vertical sequence will also replace each other laterally.
When does Walther’s Law not apply?
does not apply across unconformities where rocks are unrelated.
What are the causes of marine transgression and regression?
- Uplift and subsidence,
- Water frozen in glaciers,
- Seafloor spreading rates
What is paleontology?
The scientific study of fossils.
What are favorable conditions for fossilization?
- Hard parts,
- Rapid burial,
- Fine sediments,
- Mineralized groundwater,
- Anoxic conditions.
Where are fossils most commonly found?
In sedimentary rocks, also in volcanic ash and mudflows.
What are body fossils?
Fossils that preserve skeletal parts like shells, bones, and teeth.
What are trace fossils?
Indications of organic activity such as tracks, burrows, nests, and feces.
What are three main uses of fossils?
- Relative dating,
- Environmental interpretation,
- Evidence for evolution.
Who is Lyuba?
A 40,000-year-old frozen woolly mammoth found in Yamal Peninsula, Russia.
Who is Dima?
40,000-year-old frozen mammoth found in NE Siberia.
What is mummification in fossilization?
Preservation through drying in arid, protected environments
What does amber preserve?
Organisms like insects and even small dinosaurs in hardened tree resin.
What is tar preservation?
Fossils preserved in asphalt seeps like La Brea Tar Pits due to lack of oxygen.
What is petrification?
Turning organic material into stone by replacing it with minerals.
What is permineralization?
Fossils form when mineral matter fills the pores of bones or shells.
What is replacement?
Original material dissolves and is replaced by minerals like calcite, pyrite, or silica.
