In this laboratory exercise, you will analyzing the samples in bag A-E.Download Lab_08_a_Grain_Analysis.docx download and fill up the Microsoft word file and upload it here.
Lab8 Exercise: Grain Analysis
In this laboratory exercise, you will analyzing the samples in bag A-E.
Clastic sedimentary rocks are formed from clasts, also called grains, that are deposited in a variety of environments. The environment determines not only the size of the clasts deposited but also whether they are well sorted or poorly sorted.
In this laboratory exercise, you’ll lay a foundation for the identification of clastic sedimentary rocks by analyzing samples of sediment (Bags A through E in your lab kit) for grain size and sorting. In doing so, you’ll learn how to better determine grain size in clastic sedimentary rocks, a key clue to their identity.
For your convenience the sample bag A analysis is provided.
Instructions
Step 1: Retrieve Bag A, Bag B, Bag C, Bag D, and Bag E from your lab kit. Each bag
contains a different sample of sedimentary clasts.
Step 2: Place a white sheet of paper on a flat surface.
Step 3: Pour a sample of the contents of Bag A on the white sheet of paper.
Step 4: Analyze the sediment sample for clast size. Separate out clasts that are
representative of the largest and smallest sizes, then measure them, if possible,
using the hand lens as necessary. Enter the range into Column 1 of Figure 7.6.
Step 5. Analyze the sediment sample for clast shape. Examine at least five clasts, using
your hand lens if necessary, and referring to Figure 7.1 Textural Features of
Sedimentary Rocks to help you. Are the clasts well-rounded, rounded, or
angular? Record your observation in Column 2 of Figure 7.6.
Step 6: Analyze the sediment sample for sorting. Are the clasts about the same size? Or
is there a wide range of sizes? Determine whether the sample is well-sorted,
moderately sorted or poorly sorted, referring to Figure 7.1 to help you. Record
your observation in Column 3 of Figure 7.6.
Step 7: Determine whether the sample is clay, silt, sand, gravel, or some combination
of these. Enter your determination in Column 4 of Figure 7.6.
Step 8: Repeat the process for Bag B, Bag C, Bag D, and then Bag E. Record your
observations in Figure 7.6 below.
| Sample # | Clast Size | Clast Shape | Sorting | Identification |
| Bag A | <1/16 mm–1 mm Mixture of rounded | Mixture of rounded and angular | Moderately sorted | Sand with some silt |
| Bag B | ||||
| Bag C | ||||
| Bag D | ||||
| Bag E |
Lab 8 Sedimentary Rocks
