Science Review, Chpt 7, Apologia, General Science
Terms
undefined, object
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- Define Petrifaction
- The conversion of organic material into stone
- Define Resin
- A sticky, liquid substance that usually hardens when exposed
- Define Extinct
- 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 that will happen to the remains of a dead plant or animal is that they will decompose. Fossilization is a rare exception to this general rule.
- Which forms first, a fossil mold or a fossil cast?
- A fossil mold forms first. If a cast forms, it forms later when the mold is filled with sediment
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Describe the process of a cast forming, indicating when the mold has formed and when the
cast has formed - The remains of a plant or animal are encased in sediment and the sediment eventually hardens into rock. As the remains of the plant or animal disintegrate, a hole is left in the rock, in the shape of the original remains. That is the mold. The mold might fill up with sediment later and, when the sediment hardens, it forms a cast.
- What is required in order for petrifaction to occur?
- Petrifaction requires 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 residues and impressions similar?
- Both carbonate residues and impressions are formed by the same process. They also leave an outline of the creature.
- What is so 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?
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The four general features of the fossil record are:
1. Fossils are usually found in sedimentary rock. Since most sedimentary rock is laid down by water, it follows that most fossils were laid down by water as well.
2. The vast majority of the fossil record is made up of clams and other hard-shelled creatures.
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 another layer of the same stratified rock. - What kinds of creatures make up 95% of the fossil record?
- Clams and other hard-shelled animals make up 95% of the fossil record.
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Approximately how many species of plants and animals have gone extinct in the last 400
years: a hundred, a thousand, ten thousand, or a hundred thousand? - Approximately 1,000 species have gone extinct over the last 400 years. This is a stark contrast to the 10,000 species which some “environmentalists†claim go extinct each year!
- 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?
- A placoderm is a kind of fish. It was much like the fish we see today, but its head was covered with hard plates rather than scales. Placoderms are considered to be extinct.
- What is the uniformitarian explanation for how most sedimentary rocks 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 catastrophist explanation for how most sedimentary rocks formed?
- According to catastrophists, most of the sedimentary rocks we 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 found in different layers result from the fact that different plants and animals existed at different times in any given region.
- What is the catastrophist explanation 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.
- What major speculation must uniformitarians make when studying geology?
- Uniformitarians must speculate how millions of year of time affect the processes 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 speculation must catastrophists make when studying geology?
- Catastrophists must speculate about the nature of Noah’s flood. The speculation is 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.
- Name the steps in cast forming from the mold to the cast.
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1. A plant or animal dies.
2. The remains of the plant or animal are encased in sediment.
3. The sediment eventually hardens into rock.
4. As the remains of the plant or animal disintegrate, a hole is left in the rock, in the shape of the original remains. That is the mold.
5. The mold might fill up with sediment later.
When the sediment in the mold hardens, it forms a cast. - Define Fossil
- The preserved remains of a once living organism.