Lab 2
Lab 2
Lab 2
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Geology 435 <strong>Lab</strong>oratory Exercise #2: Due Sept. 17<br />
Unconsolidated Sediments and Rocks: Hand Samples; Binocular Microscope and Hand Lens<br />
References: Fichter and Poche, p32-56; Nichols, Ch2, p.10-24;<br />
I. Unconsolidated sediments.<br />
1. Follow the instructions on p. 39-41, Fichter and Poche, Part one Level one (omit acid reaction)<br />
and also the questions on this sheet for the 4 unconsolidated samples, listed below<br />
2. Citronelle Formation, Miocene, Florida.<br />
a. Give a complete name. (Folk, Andrews & Lewis, 1970; see attached)<br />
1. ______________________________________________.<br />
b. Does any relationship exist between grain size and grain roundness? Explain.<br />
c. What is the sorting value? (Estimate with sorting comparison charts)<br />
1. ________________________________________________.<br />
3. Guatemala; recent. (Samala River, B-2)<br />
a. Give a complete name: __________________________________.<br />
b. What is the sorting value? (estimate):___________________________.<br />
c. What is the average roundness? (estimate):______________________.<br />
4. Tecolutla, Mexico; Recent.<br />
a. Give a complete name: ___________________________________.<br />
b. What is the range of roundness present?<br />
c. Is there any relationship between grain roundness and grain type? Explain.<br />
5. Treasure Is., Florida, Recent.<br />
a. Give a complete name: ______________________________.<br />
b. What is the sorting value? _____________________________.<br />
c. What is the average roundness present? ___________________.<br />
6. Analysis<br />
a. Which sample(s) (#1 - 4) are the most mineralogically mature?<br />
b. ____________________________________<br />
c. Which sample (#1 - 4) had undergone the least amount of mechanical abrasion:<br />
___________________________________.
II.<br />
Rocks<br />
1. Follow the instructions starting on p. 47 but especially p. 49-51 in Fichter and Poche for at least<br />
6 samples from the core material available to you, AND the brown hand sample marked CH-CGL.<br />
You should choose as varied a selection of samples as possible from the cores that are available<br />
(at least one each of “conglomerate/breccia”, “sandstone”, “siltstone”, “mudstone”, and<br />
“claystone/shale”).<br />
2. You should write your observations on the “Type 2 - Siliciclastic Data Sheet” and give each rock a<br />
complete name using the procedures in the attached summary (Folk and others, 1970). Note<br />
that this naming procedure is a little different from the <strong>Lab</strong> text procedures. The attached<br />
approach is preferable.<br />
III. Thin Sections<br />
1. For the two samples with thin sections, draw a simple picture representing the texture of the<br />
rock (more than one picture if the texture is different within the thin section). Be sure to<br />
indicate the primary framework grains, matrix, cement (secondary minerals) and pores.<br />
Remember that sand typically is deposited with 25%-40% pore space. Have these rocks been<br />
altered especially with respect to original, primary porosity? What is the nature of that<br />
alteration, if any?