Unit 3: Earth's History and Evolution
1. The Law of Superposition
- Layer 1 is the youngest, and Layer 4 is the oldest.
We can use relative dating to figure out the ages of the rock by understanding that the fossils in the older rock layers are certain to be older than the fossils above it. If fossil B was 5 million years old and fossil D was 11 million years old, we can use this information to figure out that fossil C must be around 5-11 million years old.
- However, absolute age is a bit different. It is much more specific, and uses radioactive dating. Radioactive elements that form rock decay, and become different elements that are measured in half lives (the time it takes for half the atoms in a sample of radioactive element to decay). For example, Fossil A originally has 400 Carbon 14 at 5,730 years old. This means when its age is doubled, the level of Carbon 14 will decrease to 200, and we can figure out that by this point in time the fossil is 11,460 years old.
We can use relative dating to figure out the ages of the rock by understanding that the fossils in the older rock layers are certain to be older than the fossils above it. If fossil B was 5 million years old and fossil D was 11 million years old, we can use this information to figure out that fossil C must be around 5-11 million years old.
- However, absolute age is a bit different. It is much more specific, and uses radioactive dating. Radioactive elements that form rock decay, and become different elements that are measured in half lives (the time it takes for half the atoms in a sample of radioactive element to decay). For example, Fossil A originally has 400 Carbon 14 at 5,730 years old. This means when its age is doubled, the level of Carbon 14 will decrease to 200, and we can figure out that by this point in time the fossil is 11,460 years old.
3. Ice Cores
Ice cores are tubular samples that show layers of snow and ice over many years. They are very helpful in predicting the future of the Earth. Scientists are able to use information found in ice cores to discover past weather and climate patterns.
Materials such as ash, dust, fossils, and trapped carbon dioxide are found in ice cores.
Because of these discoveries, scientists can learn about the past, predict earth's future, and learn more information about fossils and creatures.
4. EVIDENCE OF PANGAEA
- Fossils - Of the same species, fossils have been found in different continents. This means that at one point in time, continents must have been connected. At the time that these species would have lived, land must have been connected, so even later when land was split, these species proved to us that continents must have been connected millions of years ago.
- Rocks - Sediment over time has proved to match up in different location all around the world. They suggest that if these areas have experienced the same circumstances, it is concluded that they were a whole land in the past.
- Continents - Just like puzzle pieces, certain parts of continents are found to have a physically perfect fit. A good example would be the edges of South America and Africa. This information helps us understand that the continents used to be joined together.
5. Diagram
- Intrusion (J)
An intrusion is when magma intrudes the rock layers above it and after it cools and hardens, it turns to igneous rock.
- Uncomformity (N)
Gaps in the rock record created when older rock is worn away and then new rock is layered overt it.
- Fault (O)
This is a break in the layers of rock.
- Intrusion (J)
An intrusion is when magma intrudes the rock layers above it and after it cools and hardens, it turns to igneous rock.
- Uncomformity (N)
Gaps in the rock record created when older rock is worn away and then new rock is layered overt it.
- Fault (O)
This is a break in the layers of rock.
10. Biological Classification
In geology, the term used for biological classification is called taxonomy.
- Starting from the top being the most general and foremost, the levels of classification for all living things are....
D - Domain
K - Kingdom
P - Phylum
C - Class
O - Order
F - Family
G - Genus
S - Species
K - Kingdom
P - Phylum
C - Class
O - Order
F - Family
G - Genus
S - Species
- Comparing the biological classifications of two organisms can be very helpful for finding out how closely related these organisms are with each other. Starting from the most general section, which is the domain, we can specify how close the organisms are by getting more specific as we go down the groups. So, if 2 organisms are found that they share the same class but nothing further, they are not very close. However, if we discover that the 2 organisms reach the division up to genus, we know that they are very closely related.