The three types of rock and how they are formed...
The igneous rock is formed from the heating and cooling of magma (melted/molten rock). When the magma erupts from a volcano, the magma is called lava. How fast the lava cools determines its texture. Hawaii is formed from igneous rock, mainly basalt. Igneous rocks include pumice, granite, and basalt.
Sedimentary rocks are formed from existing rocks. Water, wind, erosion breaks down the rock into pieces. Water, wind, ice, and gravity transport the pieces to other sites where the pieces are deposited. The pieces settle and form horizontal layers. Over a long time, the layers (strata) become pressed together in a process called lithification. Sedimentary rocks are weak and crumble easily. Sedimentary rocks include sandstone, limestone, and shale.
Sedimentary rock is distinctive because it is made up of layers, each of which has a different color.
Do you notice the different layers and different colors in this rock?
http://comp.uark.edu/~sboss/seds02.jpg
This is pahoehoe lava which will form basalt rock in Hawaii.
Metamorphic rock is formed by any rock, either igneous or sedimentary, which is transformed into a whole new rock by extreme heat or extreme pressure. Metamorphic rocks are hard and tough (compared to sedimentary). Metamorphic rocks include marble and shale.
The Rock Cycle
All three types of rock interact and are continuously being recycled into various rock forms. For example, igneous rock may be broken down into little pieces and later form sedimentary rock.
http://volcano.und.nodak.edu/vwdocs/vwlessons/lessons/Metrocks/Metrocks2.html
I found an excellent lesson where students learn about the rock cycle and properties of rocks by experimenting with crayons, observing crayons, and relating those observations and processes with the three types of rocks and how they all interact in the rock cycle.
