Sedimentary, Igneous, and Metamorphic Rocks

1. Sedimentary, Igneous, and Metamorphic Rocks Miss. Molto Earth Science

2. Sedimentary Rocks • Rocks that are made up of either pieces of other rocks, organic material ( such as fossils), or mineral crystals. • Make up about ¾ of the rocks in the world Cliff of Dover, England Made up of dead microscopic calcareous nanoplankton

3. How do Sedimentary Rocks Form? • Sediment goes through Lithification which is the process by which sediment is turned into a solid rock • Lithification includes the processes of compaction then dewatering then cementing • 1.Compaction- grains are packed more together • 2. Dewatering-during compaction water is squeezed out and pore space is decreased • 3.Cementing-temperature and pressure condition cause minerals to adhere to sediment cementing it together YouTube

4. Sedimentary Rock Classification There are 3 different classifications • Clastic – made up of particles of pre-existing rocks or minerals ex) conglomerate, shale, siltstone, sandstone • Chemical- form when minerals in a solution become supersaturated and precipitates outex) gypsum, oolitic limestone • Biochemical- forms from sediment that was derived from organic processes such as decomposition and compaction of skeletal remains ex) chalk, coal, chert, coquina

5. Chert Chalk Shale Conglomerate Limestone Coquina

6. Igneous Rocks • Formed through the cooling and of solidifying of volcanic lava or magma • Over 700 types of igneous rocks have been described, most of them having formed beneath the surface of Earth's crust Pillow Basalt under seawater Volcanic explosion

7. How do Igneous Rocks form? • Igneous rocks can be formed underground from magma or above ground from lava • Igneous rocks formed above ground are called extrusive while igneous rocks formed underground are called intrusive • Extrusive rocks form above ground from cooling lava • Intrusive rocks form Volcanic Eruption

8. Igneous Rock Classification • Igneous rocks are classified based on 3 criterion: • Extrusive or Intrusive • Crystal size- the longer a rock cools, the larger the crystals will be (pegmatite). The faster is cools the smaller the crystals will be or may not exist (volcanic glass). • Texture- glassy, fine, course, very course, vesicular (air bubble holes) etc.

9. Gabbro Basalt Pumice Course-grained Granite Pegmatite Obsidian

10. Metamorphic Rocks • Formed by the transformation of a preexisting rocks by the application of intense heat or pressure • Metamorphism can occur deep within the Earth where there is intense heat or pressure, or at a continental collision zones

11. How do Metamorphic Rocks Form? • The parent rock is subjected to intense heat or pressure • This heat or pressure causes the minerals within the rock to recrystalize into other minerals ex) Gneiss transforms into a Schist with Garnet • Or to rearrange themselves into concentrated bands of minerals ex) Gneiss has alternating bands of light and dark minerals • Youtube

12. Metamorphic Rock Classification • Metamorphic rocks are separated into two major categories • Foliated- foliated rocks have layers caused by the alignment of rocks during transformation • Non-foliated- no distinct layers • Metamorphic rocks are then further classified based on texture

13. Quartzite-non- foliated Gneiss-note the gneissic banding Phyllite Slate Schist-note the garnet after recrystallization Marble