In my US History Unit test number 15 says how do layers B & D compare in age if rock layers between be and D have eroded away what is the boundary between be and D called? I cannot find a graph related to this question
"history"
the boundary is an unconformity, and D is older
To determine the age relationship between layers B and D, we need to understand the concept of relative dating and the principles of stratigraphy.
Relative dating is a method used to determine the age of rock layers and their fossils by comparing them to other layers. The principle of superposition states that in an undisturbed sequence of sedimentary rocks, the oldest rocks are at the bottom, and the youngest rocks are at the top.
In this case, since the rock layers between B and D have eroded away, we need to find the boundary between B and D. This boundary is called an unconformity. An unconformity is a gap in the geological record, indicating that there was a period of erosion or non-deposition before the deposition of the next layer.
Although you mentioned there is no graph provided, I can explain how you can approach this question without a visual aid. Follow these steps:
1. Start with the general knowledge that, according to the principle of superposition, the oldest rocks are at the bottom, and the youngest rocks are at the top.
2. Recognize that the layers between B and D have eroded away, indicating an unconformity.
3. Determine the relative ages of the layers before and after the gap by observing any other layers in the sequence or any fossils found within the rock layers.
4. Compare the characteristics of the layers above and below the unconformity. Look for clues such as the type of rock, fossils, or any other distinguishing features that may help in identifying similar layers.
5. Make an inference based on the relative ages and the principles of superposition. If layer B is older than layer D, you can conclude that the boundary between B and D represents an angular unconformity or disconformity.
Remember that this is a general approach to the question, and without a specific context or diagram, it may be challenging to provide an exact answer. If possible, consult your textbook or ask your teacher for further guidance to ensure accuracy.