Biostratigraphy involves the study, correlation, and age-dating of rock layers based on the kinds of fossils species they contain. For more than 200 years, geologists have been using the concept of “fossil succession” to assign relative ages to rock layers.
“Fossil succession?” refers to the fact that different fossil species lived and died at different intervals of time throughout geologic history. In other words, as one looks at the layers of rock on Earth, there is a definite relative order or ‘succession’ in which each fossil species occurs inside the layers from bottom to top.
Procedure
View Animation: BiostratigraphyLinks to an external site.
https://d1lexza0zk46za.cloudfront.net/geology/animations_and_simulations/biostratigraphy/index.html
After watching the introduction, ‘click’ of the “How it is done” tab to begin the exercise.
1. In the 18th century, who was the first person to discover the fact that fossils are not just randomly distributed throughout the rock record but occur in a definite order from oldest rock layers to youngest rock layers? _____________________________________
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The young Englishman recognized that the relative vertical order of the fossils was the same in all outcrops of rocks. Some species might be missing in one outcrop but whether a fossil occurred above or below of another was always the same. Using this knowledge, he began to correlate, that is to match and order the different rock layers bearing the same fossil species.
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Using multiple outcrops of rock layers and the fossils they contained, he was able to crate a chart of the overall order in which fossil species occur through the rocks. Using this chart, he was able to predict the order of fossils in, as of yet, unvisited outcrops, and he could tell the relative order in which the different rock layers were deposited. Even though they might be hundreds of miles apart, rock layers that bore the same fossil species had been formed in the same time interval.
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2. After reviewing the “How it is done” tutorial, click on the “Try it (Beginner)” tab on the Biostratigraphy Animation Tutorial and practice correlating the fossil symbols in this exercises. Make sure to click on the “Hint” button to see how to proceed in this exercise. I am including a Screenshot below of the “correct” screen for the “Try it (Beginner)” exercise.
3. You will submit a Screenshot of the “correct” screen for the second exercise “Try it (Intermediate).” Complete the Intermediate exercise and when you get the “correct” screen, take a Screenshot of this and make sure that you include the fossil symbol stratigraphic column on the left side of screen like I did in my screenshot for the Beginner exercise.
(insert Screenshot of “correct” screen after completing Intermediate Exercises here)
4. For 5 extra credit points, complete the “Try it (Expert)” exercise and submit the “correct” screenshot in the space below. This one is a bit tricky, but just keep track of the fossil order and you should be able to solve it. This is extra credit, so if you do not complete it, no points will be taken off of your score.