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38 Cards in this Set
- Front
- Back
Principle of Superstition |
Something is always younger than anything it is on top of and always older than anything that is on top of it. |
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Law of Included Fragments |
Erosion of the oldest rock may mean there are fragments of that rock included in a younger, overlying rock. The included fragments belong to a rock older than the rock they are included in. |
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Law of Uniformitarianism |
The present is the key to the past- How something used to live by looking at a fossil and living thing. |
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Facies |
Lithofacies- rock Biofacies- biology Basic unit of geology which reflects the depositions environment. |
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Freezing as preservation |
All parts of body preserved without alteration. |
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Mummification |
“Drying out” -Dessication Preserved in Amber where the resin kills the insect by dehydrating them- produces an antiseptic environment where bacteria can’t survive. |
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Carbonisation |
The most stable molecules in a body (Carbon) Other atoms react to form new minerals which are driven off whereas the carbon is left behind as a black film, frequently seen coating an impression of an organism. |
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Petrification |
Buried quickly, water perculates underground, mineralisation of water, silica takes place of rotting body (mineral replacement) |
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Less bones |
Fossilize better as there’s less weaknesses |
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Ocean animals |
Preserve better- more sedimentation in ocean which will bury remains quicker. |
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Moulds and casts |
Buried, decomposes, leaves mould, water perculates and replaces the space. |
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Trace fossils |
Sedimentary structures produced by activity of organisms. E.g tracks, trails, burrows, borings |
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Der |
Preserved in life form, variety of sizes and ages |
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Death assemblage |
Fully grown adults |
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Derived fossils |
Fossils that are weathered out of exposed rock and deposited in new sediment |
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Trilobites |
![]() Back (Definition) |
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Trilobites |
Eyes= shallow water Large surface area= lived in soft sediment Burrows= Antennae Exclusively marine, good zone fossil (can identify what period of time one is in as they evolve quickly and have very different traits in each period) |
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Epifaunal |
Lives on seabed |
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Infaunal |
Lives on sea bed |
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Deposit feeders and filter feeders- Trilobites |
Deposit= eats detritus Filter= strains through water to absorb nutrients from it |
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Graptolites |
Also good zone fossils as they evolve quickly with distinctive groups in each new age. Always found in shales= deep marine environment. |
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Graptolites |
Stipes decrease over time |
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Brachiopods |
Still alive- can use uniformitarianism Live in or on seabed in salt water Eats by filter feeding Can study past environments as they have certain characteristics e.g winged to stop being knocked over in High energy |
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Brachiopods |
Back (Definition) |
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Brachiopods |
Back (Definition) |
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Role of the commisure |
The commisure is the line of closure of the two valves. This can be a variety of shapes depending on the environment. E.g zig zag commissure allows larger areas of entry for nutrients but ensures larger clastic particles can’t enter |
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Adductor and diductor muscles |
Adductor- close the valves Diductor- open valvss |
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Bivalves |
Filter feeders Hinges vary due to environment e.g straight hinge=low energy environment |
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Bivalves |
Back (Definition) |
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Bivalves |
Back (Definition) |
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Ammonites |
Back (Definition) |
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Ammonites |
Goniatites= simple lobes and saddles (youngest) Ceratites= simple saddles, complex lobes Ammonites- free lobes and saddles |
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Graptolites, Trilobites...cora |
Zone fossils for time and location as: Wide and plentiful distribution Ready preservation Rapid evolutionary change Easy identification of index fossils High degree of facies independence (a rock or fossil with specific characteristics) |
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Corals |
Environmental indicators: Marine conditions Warm water Clear water to let sun through for photosynthesis Shallow water High energy so it’s aerated |
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Corals |
Back (Definition) |
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Plants |
Usually found in black shale- no oxygen, no bacteria, well preserved |
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Plants |
Back (Definition) |
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Plants |
Back (Definition) |