1. Chapter 6: Rocks

2. Chapter 6.1

3. How Rocks Form

4. What Is A Rock? Rock is a group of minerals bound together. Rocks are classified by the processes that they form under. –I–Igneous – formed from the cooling of hot molten rock –S–Sedimentary – formed by the compaction and cementation of sediments –M–Metamorphic – formed the heat and pressure on pre-existing rock

5. The Rock Cycle Classifies the rocks of the crust according to their origin

6. Chapter 6.2

7. Igneous Rock

8. Igneous Rock Formation Felsic Magma –V–Very thick and slow moving –C–Contains large amounts of silica –L–Light-colored minerals quartz and orthoclase feldspar

9. Mafic Magma –H–Hotter and more fluid –C–Contains large amounts of iron and magnesium –F–Formed dark silicate minerals hornblende augite and biotite

10. Where Formed Underground magma –C–Cools slower which allows larger gains known as a coarse texture At the surface –C–Cools fast minerals are microscopic of nonexistent –S–Small crystals considered fine grain texture –N–No crystals considered glassy texture –P–Porphyry – texture where large crystals are surrounded by a fine-grained mass rock

11. Igneous Rock Descriptions –I–Igneous rocks are grouped into families according to their mineral composition

12. Granite Family –F–Form from felsic magma –G–Granite itself is the intrusive coarse-grained member of this family that is found in many mountainous areas in the U.S. –O–Obsidian – chemical composition resembles granite but has a glassy texture and dark color –P–Pumice – contains a many air holes and has a glassy texture –R–Rhyolite – fine grain igneous rock that is light in color

13. Gabbro Family –F–Form from mafic magma –G–Gabbro itself is a coarse-grained dark igneous rock –B–Basalt – the most common it is fine grained –S–Scoria – glassy texture with air holes

14. Diorite Family –N–Neither felsic nor mafic –I–Intermediate in color grays to green –D–Diorite – coarse grain –A–Andosite – fine grain

15. Igneous Intrusions –P–Pluton – a rock mass that forms when magma cools inside Earth’s interior –D–Dykes – Pluton of Igneous sheet rock that cuts across rock layers –S–Sill – Pluton of Igneous sheet rock that lies parallel to the rock layers –B–Batholiths – the largest plutons form the core the mountain ranges

16. Chapter 6.3

17. Sedimentary Rock –F–Formed from the compacting and cementing of sediments

18. Clastic Sedimentary Rock Formed from fragments of other rock Formations of clastics begins with the movement and relocation of fragments Usually transported by running water which deposits them into a body of water –R–River – bay

19. The lighter the material the farther from shore they are carried –P–Particles are sorted by size –T–The largest gravels fall out 1 st forming conglomerates followed by sands then clays The particles of the rocks become cemented together –S–Silica cements are more durable than calcite cements

20. Chemical Sedimentary Rock These rocks form when minerals precipitate or falling out of a solution –R–Rock salt (halite), gypsum and some limestone

21. Organic Sedimentary Rock Consists of sediments from the remains of plants and animals –C–Coal and limestone (shells)

22. Features of Sedimentary Rock Stratification – arrangement of visible layers Bedding Plane – line between different layers of rock Fossils – round only in Sedimentary rock it is the remains, impression or any evidence (tracks) of a plant or animals Ripple marks Nodules – fine grain silica found in limestone Geodes – spheres of silica rock found in sandstone

23. Chapter 6.4

24. Metamorphic Rock –F–Formed from pre-existing rock (parent rock)

25. Metamorphism – rocks structure is changed by pressure, heat and moisture Regional Metamorphism – occurs in mountain building areas –T–The more pressure and the higher the temperatures – higher the morph Local Metamorphism – –C–Contact – where magma touches existing rock Shale becomes horn fells which is dense and fine grained rock –D–Deformation – occurs along fault lines where the heated created by friction cause the rock to change

26. Metamorphic Rock Descriptions Foliation – tendency of rocks to form layers with visible minerals Non foliated – –B–Banded – light and dark colors –N–Non-organized – Sandstone  quartzite Limestone  marble