ROCKS CHANGE INTO OTHER ROCKS OVER TIME Igneous rocks form from molten rock.
Magma and lava form different types of igneous rocks. Igneous rocks form from molten rock that has cooled. Molten rock comes from deep within the earth.
There temperatures are hot enough to melt rock: 1400 0 -2300 0 F .
Classifying igneous rocks Based on two factors: 1) mineral composition 2) size of crystals
Rocks with larger mineral crystals are more attractive.
Rock that forms when magma cools within the Earth.
Rock that forms when lava cools at the Earth’s surface.
Extrusive igneous rocks GRANITE RHYOLITE PUMICE BASALT GABBRO
Igneous rocks make long lasting landforms. A great peak that rises out of the flat, barren desert. Ship rock formed about 1 km below the surface of the Earth 30 million years ago. It was once intrusive igneous rock. These types of formations are harder and more lasting than other types of rock. It is now extrusive igneous rock.
Great example of a natural feature on the Earth’s surface (landform) that is made of igneous rocks.
Extrusive formations The Hawaiian islands are built of basalt lava. Basalt lava flows long distances.
The volcanoes that formed them started erupting on the sea floor and over a very long time they grew tall enough to rise out of the ocean!
Extrusive formations (cont.) Mt. Saint Helens (Washington) This volcano’s lava is silica rich. This lava builds cone shaped volcanoes with steep sides.
These erupt explosively since the lava is thick, sticky and under high pressure.
PICTURES COURTESY OF: http://www.windows.ucar.edu/tour/link=/earth/geology/images/batholith_gif_image.html&edu=high http://cc.usu.edu/~sharohl/granite.jpg http://msnbcmedia3.msn.com/j/MSNBC/Components/Photo/_new/earth-540x540.widec.jpg http://beyondbooks.com/ear82/7a.asp http://www.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousTextures/4PorphyriticFinez/RhyoliteWholeRock.jpg http://geology.csupomona.edu/alert/igneous/pumice.jpg http://search.live.com/images/results.aspx?q=BASALT&go=&form=QBIR#focal=44c3c975183c8b633abce7e34c0faf8a&furl=http%3A%2F%2Fruby.colorado.edu%2F%257Esmyth%2FResearch%2FImages%2FVolcanix%2FColBasalt.jpg http://www.etankonyv.hu/sz_etankonyv/editor/upload/Epitoanyagok/gabbro.jpg http://www.dkimages.com/discover/previews/919/50487851.JPG