Reading Guide 5 -- Sedimentary Rocks

The general goal of this chapter is to figure out how to tell ancient enviroments of deposition from sedimentary rocks. In other words, we can interpret the sedimentary record to find out what the Earth was like in ancient times. What is desert today may have been a deep sea, a coral lagoon, a meandering river, and a sandy beach at various times in the past. With this paleoenvironmental information, we can begin to interpret past tectonic events and how climate has changed over goelogic time.

Most of this chapter is of about equal importance. Look at my lecture notes to see which workds are important and focus on those. try to understand what the book is saying, but don't worry about remembering other vocabulary words given in the book.

The first part of the chapter, up to about p. 120 is about how to look at a sedimentary rock. Concentrate on learning what you can learn about a paleo-environment from the mineral composition of the sediment, the sorting, and particle shape, the type of layering, and the sorting.

We won't spend much time in this class on fossil fuels, but it is interesting reading. In terms of resources, you can get an idea of how long it takes to generate these fuels. Keep this in mind for when we get to geologic time.

For the section on Common Sedimentary Rocks on pp. 124-128, concentrate again on the vocabulary we went through in class.

The end of the chapter on pp. 129-139 is really the heart of the chapter and contains the reasons we study sedimentary rocks. Spend a good bit of time using fig 4.22 to learn some of the common deopositional environments. Use the facies concept and fig 4.23 to see how to use a sequence of sedimentary rocks to see weather sea level has moved up or down. These sequences are called transgressive or regressive in the lecture notes. Skinner and Porter don't seem to use those words.

Pages 133-138 go through various sedimentary environments and how to recognize them in the sedimentary rock record. Concentrate less on trying to memorize these and more on trying to understand the logic and broader concepts that go into their identification. In other words, think about the sedimentary environments in terms of which are high energy and which are low energy; in which must the sediment travel long distances, and in which might some other type of sedimentation besides clastics dominate.

Remember, the goal is to learn how to decipher the clues left in sedimentary rocks and interpret the story that the rocks are telling.