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the conversion of the organic material into stone
a sticky, liquid substance that usually hardens when exposed to air
a term applied to a species of plant or animal that was once living but now is not
When a plant or animal dies, what is the most likely thing that will happen to its remains?
the most likely thing is it decomposes. fossilization is a rare exception to this general rule.
which forms first, a fossil mold or a fossil cast?
fossil mold. If a cast forms, it forms later when there mold is filled with sediment.
describe the process of a cast forming, indicating when the mold has formed and when the cast has formed.
when an animal or object gets buried into sediment the sediment hardens and turns to rock then the rock surrounds the object. When the object is disintegrated before the rock this creates a mold where the object was. When sediments seep into the mold and then hardens you have a cast.
what is required in order for petrifaction to occur?
water that has a lot of minerals in it
why does petrifaction usually produce fossils with more information than fossil casts?
Petrified fossils have more information than fossil casts because fossil casts retain only the shape and outer details of the fossil. When a fossil is petrified, its components are replaced with minerals. This means the entire fossil is preserved, which gives us more information than just the shape and outer details of the fossil.
what is the difference between a carbonate residue and an impression?
A carbonate residue still has a film residue of the original creature. In an impression, the film is completely gone, leaving only an outline that looks like it was etched in stone.
how are carbonate residue and impression similar?
Both carbonate residues and impressions are formed by the same process. They also leave an outline of the creature.
what is nice about fossils which have been encased in amber or ice?
Fossils encased in amber or ice do not decompose as quickly as other fossils. Thus, tissue and other soft parts which usually are not preserved tend to be preserved very well.
What are the 4 general features of the fossil record?
- 1. Most fossils are found in sedimentary rock. Since most sedimentary rock is laid down by water, it follows that most were laid down by water as well.
- 2. Nearly 95% of fossils on this planet are the fossils of clams and other hard shelled organisms. Most of the remaining fossils are of water-dwelling creatures and insects. Only a tiny, tiny fraction of the fossils we find are of plants, reptiles, and mammals.
- 3. Many of the fossils we find are of plants and animals which are still alive today. Some of the fossils we find are of plants and animals which are now extinct.
- 4. The fossils found in one layer of stratified rock can be considerably different than the fossils found in a noter layer of the same stratified rock.
What kind of animals take up 95% of the fossil record?
Clams and other hard shelled animals make of 95% of the fossil record.
approximately how many species of plants and animals have gone extinct in the last 400 years?
what is a trilobite? Are trilobites extinct?
A trilobite is a creature that lived in the water and was covered in a hard outer covering. Typically, trilobites lived at the bottom of the ocean. They are now assumed to be extinct.
what is a placoderm? Are placoderms extinct?
Placoderms are plated fish that are also assumed extinct.
what is the uniformitarian explanation for how most sedimentary rocks are formed?
According to uniformitarians, sediments are laid down slowly over millions of years. Eventually, conditions change and the sediments harden to form rocks. The conditions during which the sediments were laid down determine the type of sediment, which in turn determines the kind of rock formed.
what is the catastrophic explanation fro how sedimentary rocks are formed?
According to catastrophists, most of the sedimentary rocks www see today were formed in Noah's flood. The depth, speed, and direction of the flood waters determined what kind of sediments were laid down, which in turn determined the type of rock formed.
what is the uniformitarian explanation for why different fossils are found in different strata?
According to uniformitarians, each layer of rock represents a period of earth's history. Thus, the different fossils four in different layers result from the fact that different plants and animals existed at different times in any given region.
what major speculation must uniformitarians make when studying geology.
Uniformitarians must speculate how millions of year of time affect the processed that we see working today. At best, we have viewed how these processes work over a few thousand years. The effect that millions of years will have on the processes can only be speculated.
what major speculations must catastrophists must make when studying geology.
Catastrophists must speculate about the nature of Noah's flood. The speculation s aided by the observation of local catastrophes. Nevertheless, Noah's flood would have been much different than a local catastrophe, so the details of the flood can only be speculated.
What is the catastrophist explantation for why different fossils are found in different strata?
According to catastrophists, most of the sedimentary rock we see today is the result of the flood. Thus, the depth, speed, and direction of the flood waters determined where the fossils being preserved came from. Thus, the different fossils in different layers are the result of the fact that different kinds of fossils were trapped and preserved during different stages of the flood.
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