11.3: Activity 11B- Identifying Sedimentary Rocks
- Page ID
- 14566
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For this section, you will need the following materials before you begin:
- Sedimentary rock samples (or kit) selected by your instructor,
- Glass plate, streak plate, and a hand lens (or magnifying glass)
- Bottle of diluted HCl (optional)
- Using the kit provided, begin by separating the rocks into two piles, a clastic and a non-clastic pile. Remember, sedimentary rocks must be categorized as either clastic OR non-clastic; a sample cannot be both. For each sample number, indicate whether the sample is clastic or non-clastic by placing an X in the appropriate column below.
Sample Number |
Place an X below for Clastic |
Place an X below for Non-clastic |
---|---|---|
Using the same samples, and your Answers from questions 1 & 2, fill out Table 11.7 below.
- If the sample is clastic, determine the grain size, shape, and overall sorting.
- If the sample is non-clastic, indicate whether the sample is organic (O) or chemical/biochemical (C/BC). Then determine the dominant composition of the rock.
- Using the characteristics of each rock, identify each sample by name. Add the rock name to the final column of the table below.
Sample Number | If the sample is clastic: | If the sample is non-clastic: | Sedimentary Rock Name | |||
Grain size | Grain shape | Sorting | organic (O) or chemical/biochemical (C/BC) | Dominant composition | ||
- Chert and limestone are both fine-grained sedimentary rocks. What are two tests you can use to tell them apart?
- What characteristic distinguishes sedimentary breccia from conglomerate?
- How can sorting, rounding, and grain size be useful for understanding depositional environments? Use examples in your explanation.
Attributions
- Table 11.6: “Clastic vs. Non-clastic” (CC-BY 4.0; Chloe Branciforte, own work)
- Table 11.7: “Name That Sedimentary Rock” (CC-BY 4.0; Chloe Branciforte, own work)