Science Starter 3/13/15 Use the following terms to create a flow-chart of the rock cycle in your notebook: erosion sediments deposition compacting cementation sedimentary rock heat pressure metamorphic rock Magma lava melting cooling crystallization intrusive igneous rock extrusive igneous rock weathering

Today’s Agenda Science Starter Weather & Erosion Introduction Weathering Foldable Exit Ticket

Lesson Essential Question How do certain processes change rocks? Discovery Education Video- http://app.discoveryeducation.com/search?Ntt=weathering

Weathering Breakup of rock due to exposure to processes that occur at Earth’s surface 2 types: Physical (Mechanical)- the breakdown of rock that takes place when a rock is broken into smaller pieces of the same material without changing its composition Chemical- the breakdown or decomposition of rock that takes place when minerals are changed into different substances

Mechanical/Physical weathering Breaks rock into smaller units (increasing surface area) making chemical weathering faster.

1. Frost wedging Def: a process in which water freezes in the cracks of a rock and wedges it apart Occurs when? Where the temperature varies from below freezing to above Mostly in porous rocks and in rocks with many cracks Places with frequent freezes and thaws Ice Heaving- creates potholes; ice lifts pavement up and it collapses when it thaws

2. BIOLOGICAL Growth contributes Burrowing contributes Roots wedged into tiny pores and crevices Burrowing contributes Animals digging holes into soil Bringing rock fragments to surface

3. Unloading/Exfoliation- the peeling of surface layers from exposed bedrock Rock is uplifted by tectonic forces (ex: granite) Overlying rock is worn away which reduces pressure Upward expansion causes the granite to break along curved joints Large sheets of loosened rock break away

Chemical Weathering 1. Water Causes chemical weathering by reacting with other substances Dissolves rock into ions & forms clay minerals Acids: seeps into the ground and reacts chemically with many common minerals Carbonic acid Often breaks down limestone underground to create caverns Can collapse, causing sinkholes!

Calcite Acid Rain Dissolves completely Underground caverns Def: rainwater that contains unusually high amounts of acids that can be traced back to pollutants Increases the rate of chemical weathering

Oxidation Chemical reaction of oxygen with other substances Effective with minerals containing iron Forms rust (iron oxide)                     

Spheroidal Weathering

Rates of Weathering Weathering is usually a slow process Factors that affect the rate of weathering: Surface Exposure More surface exposed, weathers more quickly Composition of Rock Various rocks are affected differently by weathering processes Climate Warm/wet climates: both chemical and mechanical Cold/dry climates: mainly mechanical

DIFFERENTIAL WEATHERING

WEATHERING FOLDABLE!!!!

Weathering Foldable You have the next 45 minutes to create a foldable on weathering All “flaps” should have a drawing and definition Use pg 126 (Ch 5.1) to complete the foldable (ALL INFO HERE) The foldable will be worth 150 points and checked for a grade at the end of class Make sure it is nicely done and complete by the end of time!

Directions!! You will fold along the solid black lines You will cut along the dotted black lines Where it says “GLUE HERE” you will apply glue and stick the 2 pieces together If you need to see the example I will come around with my own You may listen to music, but you must stay in your seat at ALL TIMES