Rocks, Rocks and More Rocks! Igneous Sedimentary Metamorphic
Igneous Rocks • Notes: Extrusive Igneous Rocks Rock formed from lava that erupted onto Earth’s surface. Basalt – most common extrusive rock on Earth. It forms most of Earth’s ocean floor.
Igneous Rocks • Earth's Most Abundant Bedrock Basalt underlies more of Earth's surface than any other rock type. Most areas within Earth's ocean basins are underlain by basalt. Although basalt is much less common on continents, lava flows and flood basalts underlie several percent of Earth's land surface. Basalt is a very important rock.
How igneous rocks form Extrusive Intrusive
Igneous Rocks • Notes: Rock formed from magma that has hardened beneath Earth’s surface. Granite – the most abundant intrusive rock on Earth’s continents. Forms the core of many mountain ranges.
Uses: • Granite is also well-known from its many world-famous natural exposures. These include: Stone Mountain, Georgia; Yosemite Valley, California, Mount Rushmore, South Dakota; Pike's Peak, Colorado; and White Mountains, New Hampshire.
Igneous Rocks Granite is also well-known from its many world-famous natural exposures. These include: Stone Mountain, Georgia; Yosemite Valley, California, Mount Rushmore, South Dakota; Pike's Peak, Colorado; and White Mountains, New Hampshire.
Igneous Rocks • Granite
Igneous Rocks • Notes: • Texture – fine grained Rapidly cooling lava forms a fine-grained rock with small crystals. Example: Basalt - glassy texture, crystals too small to be seen without a microscope. Example: Obsidian –smooth, shiny texture like thick glass & cooled without forming crystals.
Igneous Rocks • Obsidian Obsidian on the side of a volcano
Igneous Rocks • Notes: • Texture: coarse-grained Slowly cooling magma forms coarse-grained with large crystals Example: granite and porphyry which looks like gelatin with chopped fruit
Igneous Rocks – Mineral Composition • Notes: .When rocks are high in silica they form light-colored rocks like granite. When rocks are low in silica they form dark-colored rocks like basalt
Uses of Igneous Rock • Notes: • Statues – Granite • Bridges and public buildings – Granite • Paving streets with cobblestone – Granite • Curbstones, floors, kitchen countertops – thin polished sheets of Granite
Uses of Igneous Rock • Gravel for construction – Basalt • Cleaning and polishing – Pumice • Sharp tools for cutting and scraping – Obsidian • Starting vegetable gardens (fertilizer) – Perlite, which is formed from heating Obsidian
Uses of Igneous Rock • Statues, Public Buildings - Granite
Uses of Igneous Rocks • Cobblestone streets, kitchen countertops
Igneous Rocks • Are classified by: • Origin – how they are formed • Texture – size of the crystals • Mineral Composition – silica content
Extrusive Igneous Rocks • Extrusive Igneous Rocks • Origin: forms from lava that erupts onto Earth’s surface Ex: Basalt • Texture: fine grained – rapidly cooling lava with small crystals Ex: Obsidian, Basalt Mineral Composition – dark colored rocks
Both • From volcanic activity
Intrusive Igneous Rocks • Origin: forms from magma that has hardened beneath Earth’s surface • Texture: coarse grained – slowly cooling magma with large crystals Example: Granite , Porphyry Mineral Composition: light-colored rocks that are high in silica Ex. Granite