Analyze the sedimentary rocks in Fig. A6.1.1, or actual rock samples of them if

Question

Analyze the sedimentary rocks in Fig. A6.1.1, or actual rock samples of them if available. Below each photograph, descri briefly the rock's composition (what it is made of) and texture (the size, shape, and arrangement eof current knowledge, and complete the worksheet with your current level of ability A 1 cm Observation: does not fizz in acid Observations: fizzes in acid; mostly shells 1 cm 1 cm Observations: does not fizz in acid; intergrown crystals; salty Observations: does not fizz in acid, very fine grained 1 cm Observations: does not fizz in acid; grains average-0.5 mm diameter Observation: fizzes in acid Figure A6.1.1 tinns and descriptions of sedimentary rocks in part A. Then

Explanation / Answer

1. The rock is conglomerate. It consists of larger fragments (greater than two millimeters in diameter) which are bounded by finer grains known as matrix. The rounded clasts of conglomerate can be mineral particles such as quartz, or they can be sedimentary, metamorphic, or igneous rock fragments. The matrix that binds the large clasts together can be a mixture of sand, mud, and chemical cement.

2. It is Shelly limestone. Shelly limestone is a highly fossiliferous limestone. It is composed of a number of fossilized organisms. Broken shells fragments are bounded together with calcite. So, it fizzesin acid. Fossilized organisms are brachiopods, bryozoans, crinoids, sponges, corals and mollusks etc.  

3. This rock is Evaporite which is water-soluble mineral sediment. It is concentrated and crystallized by the evaporation from an aqueous solution. The mineral grains are gypsum and halite etc. So, it does not fizz in acid but it tastes like salty. Those rock shows intergrowth texture.

4. The rock is shale, fine-grained clastic sedimentary rock which is composed of mud or clay minerals and silt-sized particles of other minerals, especially quartz and calcite. Black shale results from the presence of greater than one percent carbonaceous material. Clays are the major constituent of shales and other mudrocks.

5. This is limestone, containing calcium carbonate (CaCO3) in the form of the minerals calcite or aragonite. It contains an abundance of fossils or fossil traces. The rock shows plant fossil traces. As it contains calcium carbonate so it reacts with acid and shows evervations.

6. This is sandstone. The grain size is ~0.5mm or medium sand size particles. Sand-size particles range in size from 1/16 millimeter to 2 millimeters in diameter. The rock is composed of sand-size grains of mineral and rock fragments which are bounded by finer matrix of silt- or clay-size particles and/or cement.  

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