GEOL 1301 - Lab 04 - Sedimentary Rocks

GEOL 1301 Name: Jonathan Venegas Sedimentary Rock Lab Learning and Lab objectives: Sedimentary rocks form from particles (i.e., sediments) such as clay, sand, and/or gravel, that travel some distance from their source, get deposited and then finally lithified into a new rock. In this lab, you will identify a set of common sedimentary rocks as you did in Lab 1 and 2. The categorization of sedimentary rocks relies heavily on texture that you observe within each sample. “Grain size” and “rounding” (G.&J.; pg. 158-159) provide information of the conditions the sediments experienced during the transportation prior to deposition. In addition, the composition of the sediments may provide you with information about where the source of the sediments was. For example, if you see a great deal of quartz in your sedimentary rock, it is unlikely it came from a basalt near a mid-ocean ridge and was more probably sourced from continental crust. Terminology and lab instructions: At the beginning of the lab your lab instructor will review the important terminology below, which was introduced last week in the lecture section of GEOL1301. They will also introduce some of the common sedimentary rocks and their formation mechanisms. Please complete the Table 1 on page 2 of this lab using the following criteria: Grain Size Rounding Composition Other observations  Gravel > 2 mm  Sand 0.06-2 mm  Silt 0.004-0.06 mm  Clay < 0.004 mm  Angular  Sub-rounded  Well-rounded Can you identify any minerals in this rock?  Layering  Fissility  Color  … We have also included two good, online identification keys: http://geology.about.com/od/rocks/a/Rock-Tables.htm https://openpress.usask.ca/geolmanual/chapter/overview-of-sedimentary-rocks/ Samples included in this lab are:  Chalk  Chert  Conglomerate  Fossiliferous Limestone  Peat  Rock Gypsum  Sandstone  Shale Important notice : In this lab you will be using hydrochloric acid (HCl). This is a dangerous liquid for skin and eyes, and it can also damage clothes. – By starting to work on this lab, you acknowledge that you have read and understood the dangers associated with the use of HCl. If you don’t want to use it, ask your lab instructor to use it for you. Don’t forget to put your name on the worksheet and submit it to your instructor! 1

Name: Jonathan Venegas Table 1: Observations and classifications of rock samples. Sample Number Grain Size Rounding Sorting Composition Other Observations Rock Name 1 Gravel Angular Poorly Rock Fragments Different shades of black and brown are composed of many different rocks Conglomerate 2 Clay Hard to tell Well Quartz Very Smooth and shades of brown Chert 3 Gravel Sub-rounded Poorly Calcite Very Rough, crystal, Smooth shapes, Inconsistent Fossiliferous Limestone 4 Sand Well-Rounded Well Feldspar, Quartz Very rough, and the marks are powdery. Sandstone 5 Silt Well-rounded Well Clay, Quartz Very powdery, White residue left behind. Chalk 6 Clay Hard to tell Well Clay, Quartz Smooth, dark black color easy to break as well. Shale 7 Silt Sub-Rounded Partly Quartz Smooth and rough around the roc, not grainy but scratches easily Rock Gypsum 2