Question

1. what are the three characteristics of an index fossil?

objective 2: relative dating

1. what is uniformitarianism and what does it mean?
2. what does relative dating tell us about rock layer ages?
3. list and explain the 3 main dating principles that steno created.
4. explain inclusions and unconformities and how they help with relative dating.
5. how can geologic time “go missing” in an unconformity?
6. place the letters and geologic events (that may be labeled with letters) in order from oldest to youngest. then list where steno’s laws were applied to help order the layers and events correctly.

Explanation:

1. Index fossil characteristics: Widespread distribution, short - lived species, easily recognizable.
2. Uniformitarianism: The idea that the same geological processes that operate today operated in the past at similar rates.
3. Relative dating: Tells the order of rock layer ages, not the actual age. Older layers are usually at the bottom.
4. Steno's principles: Law of superposition (older layers at bottom), law of original horizontality (layers are originally horizontal), law of lateral continuity (layers extend laterally).
5. Inclusions and unconformities: Inclusions are older rocks within younger rocks, helping to establish relative age. Unconformities are gaps in the rock record, indicating a period of erosion or non - deposition, useful for relative dating.
6. Geologic time in unconformity: Erosion or non - deposition during an unconformity can cause geologic time to seem "missing" as rock layers representing that time are absent.
7. Ordering geologic events: Without specific data on the events in the diagram, in general, applying Steno's laws like superposition helps order layers from oldest at the bottom to youngest at the top.

Answer:

1. Widespread distribution, short - lived species, easily recognizable.
2. The idea that the same geological processes that operate today operated in the past at similar rates.
3. Tells the order of rock layer ages, older layers usually at the bottom.
4. Law of superposition (older layers at bottom), law of original horizontality (layers are originally horizontal), law of lateral continuity (layers extend laterally).
5. Inclusions are older rocks within younger rocks, useful for relative age. Unconformities are gaps in the rock record, useful for relative dating.
6. Erosion or non - deposition during an unconformity causes geologic time to seem "missing".
7. Without specific data on the diagram's events, superposition helps order layers from oldest at the bottom to youngest at the top.