6e Geography
7 Natural Wonders of the World: The Grand Canyon
Name_________________________
Rock type
How it forms
Examples
Sedimentary
Formed by compacting/cementing of sediments.
Limestone (including chalk),
sandstone, shale, clay, mudstone
Notes: Usually weaker than the other two forms, though
some such as limestone can be tough. These rocks usually
form in layers.
Igneous
Formed by cooling molten lava by volcanic activity
underground = intrusive on the ground = extrusive.
Granite, basalt, obsidian, pumice
Notes: made up of interlocking crystals. Tough and
resistant to erosion.
Metamorphic
Altering other rocks via heat or pressure.
Notes: Also crystalline. Often have banding and layering.
Usually very tough and resist erosion
Slate, marble, gneiss (pronunciation;
nice), quartzite