Sedimentary, Igneous, and Metamorphic Rocks

Sedimentary, Igneous, and Metamorphic RocksMiss. MoltoEarth Science

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Sedimentary RocksRocks that are made up of either pieces of other rocks, organic material ( such as fossils), or mineral crystals.

Make up about of the rocks in the world

Cliff of Dover, EnglandMade up of dead microscopic calcareous nanoplankton2Emphasize the fact that sedimentary rocks are composed of consolidated sediment and that sediment can be in many different forms.2How 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 together2. Dewatering-during compaction water is squeezed out and pore space is decreased3.Cementing-temperature and pressure condition cause minerals to adhere to sediment cementing it together

YouTube3Clearly describe the processes of compaction dewatering and cementingThis can be exemplified by putting pebbles in a tall cylinder, adding water, then pressing down the pebblesPresent the YouTube video so students can get another visual that shows the processes3There 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 out ex) 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, coquinaSedimentary Rock Classification4Emphasize that although sedimentary rocks can be formed from very different sediment, they are all still composed of preexisting materials that have undergone lithification4

Chalk

Shale

Conglomerate

Chert

Limestone

Coquina5Briefly describe each rock and whether they are clastic, biochemical, or chemical and why.5Igneous RocksFormed 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 explosion6

Explain how magma and lava cool and the rate at which they cool causes differences in the rocks6How 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 7Volcanic EruptionExplain difference between lava and magma and remind students to not confuse the twoShow YouTube video of a volcanic erruption

7Igneous Rock ClassificationIgneous rocks are classified based on 3 criterion:

Extrusive or IntrusiveCrystal 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.

8Emphasize the fast that cooling rate has a direct effect on crystal size and texture89

Course-grained Granite

Obsidian

Pumice

Pegmatite

Basalt

GabbroBriefly describe each rock and talk a little about their texture and if they are extrusive or intrusive910Metamorphic RocksFormed by the transformation of a preexisting rocks by the application of intense heat or pressureMetamorphism can occur deep within the Earth where there is intense heat or pressure, or at a continental collision zones

Metamorphic rocks are formed from other rocks that have been altered and transformed1011How 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

The YouTube video will show students that other rocks are changed to form new rocks1112Metamorphic Rock Classification Metamorphic rocks are separated into two major categoriesFoliated- foliated rocks have layers caused by the alignment of rocks during transformationNon-foliated- no distinct layers

Metamorphic rocks are then further classified based on texture

Since explaining the classification of metamorphic rocks can be confusing, the chart will be a clear visual 1213

Gneiss-note the gneissic banding

Phyllite

Schist-note the garnet after recrystallization

Slate

Quartzite-non- foliated

MarbleBriefly describe each rock and their texture and if they are foliated or non-foliated13