Science: History of Planet Earth Flashcards
How do fossils provide clues about the environment where the organism lived?
For example, they can show whether the organism lived on land or water, or what was the climate in the organism’s environment.
Why do some rock layers have different colors?
Each layer is made up of different sediments, and minerals in different sediments might become colorful when they combine with air.
Why do scientists study the order of strata?
By comparing the order of rock layers, they can try to determine the ages of fossils and layers. They do this kind of research by taking core samples of rock layers.
By studying rock strata, scientists can also construct a fossil record to tell how organisms changed over time, as well as a geologic time scale that span the entire history of earth.
True or false: rock strata are always accurate
False.
Rock strata can change. For examples, sometimes there is movement along the surface of the earth near faults and rock layers can shift, where older layers might end up closer to the surface than younger layers.
Give an example of how fossils can tell us how an environment changed over time.
In parts of North America that are far from the ocean today, marine fossils have been found, which tells us that at one point, certain parts of North America which is dry land today were once covered by water.
True or false: an organism which is very unique looking, can be found in many places, and lived in long period of time is a good index fossil
False.
The rules of index fossils are:
1) distinctive and unique looking enough to be easily identified
2) common and can be found all over earth
3) abundant where a great number can be found
4) lived a relatively short period of earth’s history
So an organism that lived in a long period of time is not a good index fossil.
What is the K-T boundary?
It is a well known key bed. It is a thin layer of clay that formed from a meteorite impact that happened 66 million years ago.
How did the study of key bed lead scientist to form a theory of how dinosaurs became extinct?
Scientists took samples from key bed layers from all over earth. They found that when dinosaurs became extinct, there was a substance called iridium in the key bed layer. This substance is not common on earth, so this led scientists to believe that a large asteroid from outer space crashed on earth, which led to climate change where many plants and animals (including dinosaurs) could no longer survive.
