Question

3. Stratigraphy helps paleontologists understand the sequence of events in Earth's history.

A. What are two of the principles of stratigraphy? (4 points)
B. How is each principle used to make it easier for geologists to understand Earth's past? (6
points)

Answer 1

A. Two of the principles of stratigraphy are:

Law of Superposition: This principle states that in a sequence of rock layers, the oldest rocks are found at the bottom, and the youngest rocks are found at the top.

Principle of Faunal Succession: This principle states that different rock layers contain different fossil assemblages that succeed each other vertically in a predictable order.

B. Each principle is used to make it easier for geologists to understand Earth's past in the following ways:

Law of Superposition: This principle allows geologists to determine the relative ages of rock layers, even if they are not in the same location. By comparing the rock layers in different locations, geologists can create a timeline of Earth's history and understand how different events occurred in different places at different times.

Principle of Faunal Succession: This principle allows geologists to use fossils to date rock layers. By examining the fossil assemblages in different rock layers, geologists can determine the relative ages of those layers and create a more precise timeline of Earth's history. This principle is also useful for correlating rock layers between different locations, as similar fossil assemblages can indicate that two rock layers are of similar age.

Overall, the principles of stratigraphy provide geologists with a framework for understanding the sequence of events in Earth's history. By using these principles to analyze rock layers and fossils, geologists can create a more complete picture of the past and better understand how our planet has changed over time.

Step-by-step explanation:

Answer 2

Law of Superposition - This principle states that in a sequence of undisturbed sedimentary rocks, the oldest rocks are at the bottom and the youngest are at the top. This principle allows geologists to determine the relative ages of rocks and fossils based on their positions within the rock layers.

Principle of Original Horizontality - This principle states that sedimentary rocks are originally deposited in horizontal or nearly horizontal layers. Any deviations from this horizontal orientation are the result of subsequent geological events, such as folding or faulting. This principle allows geologists to identify rocks that have been tilted or overturned, which can provide clues to the tectonic history of an area.

B. The Law of Superposition and the Principle of Original Horizontality are used in the following ways to make it easier for geologists to understand Earth's past:

Dating of rocks and fossils - By applying the Law of Superposition, geologists can determine the relative ages of rocks and fossils within a sequence of sedimentary rocks. This information can be used to construct a geological time scale, which provides a chronological framework for Earth's history.

Interpretation of depositional environments - The Principle of Original Horizontality helps geologists to interpret the depositional environments in which sedimentary rocks were formed. By analyzing the sedimentary structures and fossils within the rocks, geologists can reconstruct the ancient environments in which they were deposited, such as river channels, deltas, or shallow marine environments.

Identification of geological events - Both principles can be used to identify geological events that have affected the sedimentary rocks, such as folding, faulting, and erosion. By analyzing the orientation of rock layers and the relationships between different rock units, geologists can reconstruct the geological history of an area and infer the types of tectonic forces that have shaped it.

Step-by-step explanation: