Investigation 2 Weathering and Erosion Part 1 Sorting

Investigation 2: Weathering and Erosion Part 1: Sorting Earth Materials

Focus Question • How big are rocks?

Rock Mixture • Each group: • One cupful of the mixture • Two paper plates • Two sheets of newspaper • Two hand lenses • Two metric rulers

Analyze • Divide the rock mixture between the two paper plates • Each pair examines and records observations in journal • Put newspaper under the paper plates for easy clean up

Sorting • How did you sort your material?

Wentworth Scale of Rock Particle Size • Boulder – Above 256 millimeters (mm) • Cobble – 64 -256 mm • Pebble – 4 -64 mm • Gravel – 2 -4 mm • Very coarse sand – 1 -2 mm • Coarse sand – 0. 5 -1 mm • Medium sand – 0. 25 -0. 5 mm • Fine sand – 0. 125 -. 025 mm • Very fine sand – 0. 0620. 125 mm • Silt – 0. 004 -0. 062 mm • Clay –Less than. 004 mm

Measuring Time! • Each pair needs a ruler with millimeters • You have time to measure all four piles • Determine which category each falls into based on the scale • Add this information to your notebooks

Rock Sizes in Nature • Today I handed you a cup of rocks that are all different sizes. Do rocks always appear in nature mixed up by size? • Where in nature can you find sand? • How does sand get separated from other sizes of earth materials in nature? • What would cause sand to become separated from other sizes of materials in a desert? • Would wind separate materials in your mixture? • Which size of materials would be moved easily by wind?

Sorting • The process of separating earth materials by size

Wind Test • GENTLY blow on the mixture • Which particles move easiest?

Small-Particle Categories • Press finger on the dust and rub between fingers • If gritty (rough), silt particles • If smooth, clay particles

Rock Categories • How are each of the particles in the earthmaterials mixture alike? • How are the particles in the mixture different? • How are the sand-sized particles like the gravel pieces?

Wrap-Up • Focus Question: How big are rocks? • Record vocabulary in Index

Homework • Visit your backyard, local park, the school, or somewhere else • Inventory the types of rocks you discover