The fault (blue) could have occurred before the dike (red), or the dike could be older than the fault! But, both must be younger than the layers of sedimentary rock, because they cut across those layers. There is only one logical answer for the example above. Are there any other options besides the one you came up with first? Step 5: Are there any alternative explanations that are equally valid? If two events (such as two faults, or a fault and a dike) do not overlap with each other, it may be difficult to tell which one happened first. Now, it might be helpful to check by going from the youngest to the oldest event. Discovering Geology introduces a range of geoscience topics to school-age students and learners of all ages. It is intended for amateur geologists, students and teachers looking for an overview of the geology of the British Isles. Use the principles of relative age dating to make sure the order makes sense. Make-a-map is an interactive geological map of the British Isles. Start at the bottom (oldest) and list to the youngest event. Step 3: List the letters in the order in which they occurred. Weathering and erosion occurred, forming a layer of soil on top of layer A.Fault E formed, shifting rocks A through C and intrusion D.When layers A-B-C were present, intrusion D formed.Separate geologic maps are available for Alaska, Hawaii, and Puerto Rico. Data for the District of Columbia is included with Maryland. Include events like folding, faulting, and erosion in your story. Digital geologic maps of the US states with consistent lithology, age, GIS database structure, and format. Step 2: List out the story of events and rocks. In this case, we see that layer C is the oldest because it is on the bottom. It is best to tell the story of what happened in the cross section by trying to find the thing that happened first (rather than starting with the last thing that happened). What is the strategy for completing a relative age exercise?

Geological age map