Gen Science Module 7 Flashcards
Fossil
The preserved remains of a once-living organism.
Petrifaction
The conversion of organic material into stone.
Resin
A thick, slowly flowing liquid produced by plants that can harden into a solid.
Extinct
A term applied to a once living species but now is not.
When a plant or animal dies, what is the most likely thing that will happen to its remains?
They will decompose. Fossilization is a rare exception to this rule.
Which forms first: a fossil mold or a fossil cast?
Fossil mold.
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?
Fossil casts retain only the shape and outer details. When a fossil is petrified its components are replaced with minerals - preserving the entire fossil.
Can you learn much about the thickness of an organism from carbonized remains?
No, because they come as a result of the organism being squished, so that only gives you a two dimensional view.
What type of organism is most likely to leave carbonized remains?
Plants.
What is so nice about fossils that 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 four general features of the fossil record?
The four general features of the fossil record are:
What kinds of creatures make up the vast majority of the fossil record?
Clams and other hard-shelled animals make up 95% of the fossil record.
years: a hundred, a thousand, ten thousand, or a hundred thousand?
Approximately 1,000 species have gone extinct over 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?
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 years 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.
