Download Age of Rocks, Fossils, Adaptations, and Geologic Time Study Guide

Age of Rocks, Fossils, Adaptations, and Geologic Time Study Guide Answer
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1. A. Organism dies in a watery environment.
B. Layers of sediment cover the organism before the organism can decay or be eaten.
C. Mineral rich water seeps into the cells of the organism.
D. The minerals stay in the cells and harden---forming the fossil. The sediment becomes rock.
E. The rock is weathered and eroded and fossil is eventually exposed.
In layers of sedimentary rock, the oldest fossils are found in the bottom layers. Fossils that are in the same rock
layer are approximately the same age.
2. Only the hard parts will become fossilized. Such as bones, teeth, shells, and woody stems. The soft parts would
be more likely to decompose quickly in the mud or water or get eaten by scavengers.
3. The fossil record tells us that organisms have changed over time moving from less complex to more complex. It
tells us what organisms eat and what ate them and tells us what type of environment the organism lived in. By
looking at an organism we can predict the type of environment that an organism lived in. When looking at fossil
layers we can see how environments have changed over time. Fossils can tell us if an area in the past was a
shallow bay, an ocean bottom, or a freshwater swamp. They can also provide us evidence of past climates of a
region. The fossil record has weaknesses because not all organisms fossilize.
4. Molds and Casts both copy the shape of ancient organisms. A mold is a hollow area in sediment in the shape of
an organism or part of an organism. It forms when the hard part of the organism is buried. A cast is when water
carrying dissolved minerals seep into the hollow area. When the minerals and sediment harden it becomes a cast.
A cast is like a 3D replica of an ancient organism. Molds and casts are opposites of each other.
5. Trace fossils provide evidence of the activities of an ancient organism. Some examples are foot prints, burrows,
trails left behind, eggs, and nests. The traces are covered by sediment and eventually harden.
6. Remains of an organism become petrified (turned into stone) by minerals replacing all or part of an organism.
Example: Wood. –Sediment covers wood. Water rich in minerals seep into the spaces in the plants cells. Over time
the minerals come out of the solution and harden, filling all of the cell spaces. Some of the original wood remains
but the minerals have preserved it.
7. A carbon film is an extremely thin coating of carbon on rock. When sediment buries an organism, some of the
materials that make up the organism evaporate, leaving carbon behind. This process can preserve delicate parts of
plant leaves and insects. All organisms contain carbon.
8. The geologic time scale is a record of life forms and geologic events in Earth's history.
9. The major divisions of geologic time are Eras and periods.
10. The law of superposition states that in horizontal layers of sediment, the oldest rock layer is found on the
bottom. The older rock layers had to be laid down first for other layers to be formed on top. Younger rock layers
are found on the top. Scientists use the principle of superposition to help put rock layers and fossils found in rock
layers in relative order.
11. An extinction is when the last organism of a given species dies. There are no more of this species on Earth and
they will never appear again. A mass extinction is when numerous species become extinct at the same time.
12. Organisms become extinct when something affects the environment in which the organism lives and the
organism cannot adapt to the changes. These changes can be abiotic (changes to the atmosphere, temperature or
land) or biotic (loss of food source, habitat, or predation—getting eaten by a new predator).
13. Weathering is the breaking down of rocks by physical or chemical means. Erosion is the movement of smaller
pieces of rock called sediment to new locations by wind, water, glaciers, and gravity.
14.
A . Freeze it – When carbon dioxide and methane are removed from the atmosphere, the UV rays from
the sun escapes back into space and the climate cools on Earth. As the temperatures drop, the organisms may not
be able to adapt and they will die. If plants die, then herbivores will die, then carnivores will die. Temperature
decreases can cause sea levels to decrease which can kill marine organisms.
B. Boil it – When there is an increase in carbon dioxide and methane in the atmosphere, then UV rays
from the sun will be trapped in the atmosphere, causing the climate to warm. As temperatures get warmer on
Earth, organisms that are not able to adapt will die. Temperature increases can also increase sea levels, causing
land organisms to die.
C. Drop a rock on it – An asteroid hits the earth and causes ash and smoke to go into the atmosphere.
Small rocks and molten fragments will “rain” down on Earth for hundreds of miles causing forest fires. The ash and
smoke in the atmosphere blocks the sunlight from getting to the Earth’s surface. This causes temperatures to
change and prevents plants from going through photosynthesis. Plants will die, and then organisms that eat plants
will die. The impact from the rock hitting the Earth can cause more Earthquakes and Tsunamis which can also kill
organisms.
D. Cover it with Ash and Lava – Huge Volcanic eruptions from multiple volcanoes puts huge amounts of
ash and dust into the atmosphere. This ash and dust blocks the sunlight from getting to earth’s surface.
Organisms can die from the initial volcanic eruption, being buried by lava, or can die from inhaling dust and gas in
the air. Additionally, organisms die because there is less sunlight for plants to use for photosynthesis. This can
affect the food chain.
14. The underlying cause for all mass extinction events is when climate changes faster than organisms can adapt.
15. Natural Selection is when organisms that are best suited for the environment are better able to survive and
reproduce.
16. There are different environments all over the earth, and organisms develop characteristics that allow them to
survive in their specific environments. Over time, a species that lives in different environments may evolve into
multiple different species.
1.
fossils.
2.
Fossil record
3.
Petrified
4.
Carbon film
5.
Extinct
6.
Relative
7.
Index
8.
Precambrian
9.
Cenozoic
10. Continents
11. 4.6 billion
12. Species
13. Adaptation
14. Reproduce
15. Variations
16. Genes
17. Species
18. Sedimentary
19. Petrified
20. Punctuated Equilbrium (evolution)
21. erosion