Science Review: Land Formations (Rocks, Minerals, Soil, etc.)
Rocks
Are classified according to the way they form:
1. Igneous: formed from melted rock: magma/lava that has cooled
2. Metamorphic: squeezed and heated to high temperatures, when it cools and hardens it
becomes metamorphic rock
3. Sedimentary: layers of clay, sand, mud, rock are squeezed together and solidify
Minerals
Materials in Earth’s crust made of crystals
Properties:
Color
Luster- shiny-ness
Streak- color of the powder when rubbed
Hardness- what can scratch it?
Soil
Broken down rocks, minerals, decaying plants and animal matter
Humus- layer of decaying plants, animals and animal matter (like scat/waste)
3 layers of soil:
Topsoil: humus is found here
Subsoil: minerals, clay, sediment washed out of topsoil or broken down bedrock
Bedrock: bottom rocky layer
Weathering and Erosion
Weathering- breaking down of rocks into smaller rocks- sediment
~water (flowing, waves, rain, etc.)
~ice
~wind
~roots of plants
Erosion- moving sediment away (washing away)
Deposition- putting new sediments in place
Forms: beaches
Dunes
Deltas
Example: A friend lives on Marblehead Neck and has a private beach at the water line. After a
storm, the sand is not there! It is all rocks! It has been washed away- this is erosion. That sand
was swept over and dumped by the water onto Devereux Beach- this is deposition.
Earth Forms
Mountains- form when plates push together, fold or crack
Volcanoes- formed from magma (inside the Earth) erupting out to become lava (on top of
surface). Can also throw rocks, boulders, ash and hot gasses
Earthquakes- sudden shaking movement of the ground made from plates of Earth moving
Fault- cracks in the Earth’s crust.