Earth's History
Where would you find the oldest rock layers and fossils in an undisturbed stack of sedimentary rock?
At the very bottom. Use the Law of Superposition.
About 97% of Earth's water is salt water. Of the remaining 3% that is freshwater, where is the majority of it trapped or located?
It is frozen in glaciers and ice caps.
If a lake has very high turbidity, what does the water look like, and how does it affect the plants living at the bottom?
The water looks cloudy or muddy. This blocks sunlight from reaching the plants at the bottom, so they cannot perform photosynthesis and will die.
Classify the following as renewable or nonrenewable: Solar, Natural Gas, Biomass, and Nuclear.
Solar and Biomass are renewable. Natural Gas and Nuclear are nonrenewable.
What major event marked the beginning of a significant, rapid increase in carbon dioxide emissions and global temperatures?
Industrialization.
What are the two specific characteristics an organism must have to be considered a good index fossil?
They must have lived for a short period of time and been found in many different places (widely distributed)
Explain why estuaries are often called the nurseries of the ocean.
They are protected areas where freshwater and saltwater mix (brackish), providing a nutrient-rich habitat for many young marine organisms to grow safely
A scientist finds that a body of water has a pH of 4. Is this water healthy, and how would you classify it?
No, it is not healthy. A pH of 4 is highly acidic. Most aquatic life needs a neutral pH (around 6-7) to survive.
What are the nonrenewable energy sources that are most commonly used in the U.S, and what is the primary byproduct when burning it?
Fossil Fuels (Oil, Coal, & Natural Gas). The primary byproduct is carbon dioxide, which contributes to global warming.
What specific human activity has contributed most to global temperature rises?
The burning of fossil fuels (coal, oil, and natural gas) for energy and transportation is the primary activity
Fossils of ancient sea shells on the top of a high mountain range are found. What does this evidence reveal about the history of that land? (*Bonus points if you identify what geological phenomenon occured)
It proves that the land was once covered by an ocean. It was pushed upward by tectonic plate activity. (Uplift)
What is a river basin, and how does it differ from a stream?
A river basin is the entire land area that drains into a large river. A stream is just one small channel of water within that larger basin
Explain the relationship between water temperature and Dissolved Oxygen.
As water temperature increases, the amount of dissolved oxygen decreases. Cold water holds more oxygen than warm water.
Many power plants have switched from coal to natural gas because it burns cleaner. However, what is one major environmental risk associated with fracking?
Fracking can lead to the contamination of groundwater and can cause small earthquakes due to the high-pressure injection of fluids into the earth.
How does the Greenhouse Effect work in order to warm the Earth?
Greenhouse gases trap heat within the atmosphere instead of escaping into space.
Why is the fossil record considered incomplete? Provide at least two reasons why many ancient organisms never became fossils.
-Organism destroyed by erosion, melting, or crushing of rock layers
-Scavengers ate the bodies
-Volcanic activity
Describe the relationship between salinity, temperature, and water density in the deep ocean.
Cold water and high-salinity water are more dense, causing them to sink. This creates deep-sea currents that drive global ocean circulation.
Why are mayflies and stoneflies called bio-indicators?
They are organisms that are very sensitive to pollution. Their presence or absence tells scientists how healthy the water is without having to run chemical tests.
Explain the concept of stewardship in terms of energy and provide one example on how to conserve energy.
Stewardship is the responsible management, efficient use, and sustainable development of energy to meet current needs without using up energy for future generations. Answers may vary for how to conserve energy.
If humans continue to burn fossil fuels, how will this affect Earth's water distribution?
Rising temperatures cause glaciers and polar ice caps to melt, leading to rising sea levels. It also speeds up evaporation, which can lead to more frequent and severe droughts in some regions while causing extreme flooding in others.
There are four sedimentary layers (A,B,C,D) with an igneous intrusion cutting through the bottom three layers (D,C,& B) but not the top layer (A). Between layer B and layer A, there is a jagged, uneven line. If the igneous intrusion is dated ~250 million years old, what can you conclude about the age of Layer A and the cause of that jagged line?
Layer A must be younger than 250 million years. The jagged line is an unconformity, which proves that a period of erosion occurred, removing some of the rock record before Layer A was deposited
A scientist notices that a specific area of the ocean has a sudden increase in nutrient levels and a drop in temperature at the surface. Identify this process and explain its importance to the local food web.
This is upwelling. It brings cold, nutrient-rich water from the deep ocean to the surface, which supports large populations of plankton and fish.
A city monitors a lake after a massive fertilizer spill:
>Day 1: Nitrates are high, Turbidity is low, and DO is normal
>Day 7: Turbidity is high, and DO is very high
>Day 14: DO has dropped to 2 mg/L
Explain the biological reason for the DO spike on Day 7, and identify what phenomenon occured.
The Day 7 DO spike was caused by an algal bloom due to high nitrates/phosphates from fertilizer. This is clled eutrophication.
A coastal town wants to switch to 100% hydroelectric and wind power. What are two potential ecological drawbacks this town might face despite these being renewable energy sources?
Hydroelectric dams disrupt fish migration and destroy upstream habitats. Wind turbines can harm migratory birds and bats if placed in their flight paths, wind turbines also require land.
Explain the difference between mitigation and stewardship in the context of Earth's resources.
Mitigation refers to active efforts to reduce the severity of climate change Stewardship is the responsible management and protection of existing natural resources.