Introduction to Rocks Geology Unit 2
What are Rocks? • Rocks are simply aggregates (combinations) of one or more minerals. • Rocks can be hard or soft, vary in size. • Integral part of human history • First tools were made of stone • Shelter • Monuments, etc. • The study of rocks is the science of petrology.
Rock system of classification • There are many types of rocks, geologists classify rocks based on HOW the rocks were formed. • There are three categories of rocks: • 1. Igneous • 2. Sedimentary • 3. Metamorphic
Igneous Rock • How do they form? • Forms directly from liquid rock (magma). • Liquid rock cools and hardens to form Igneous rock. • Liquid rock inside the earth is Molten magma • Liquid rock that exits onto the earth’s surface is known as lava.
Examples of Igneous Rock Source: http://www.geog.ucsb.edu/~dylan/mtpe/geosphere/topics/rx/igneous.html
Sedimentary Rock • Result from pre-existing rock • Sedimentary Rock = layered rock. • Rocks break down into pieces due to environmental forces (wind, water, ice)….more on this later • Pressure (due to weight of sediments) solidify these rock particles together. This happens continuously, forming layered rock.
Examples of Sedimentary Rock • Gros Morne National Park, Newfoundland
Examples of Sedimentary Rock • Parrsboro, Nova Scotia
Examples of Sedimentary Rock… • Hopewell Rocks, NB
Examples of Sedimentary Rock.. Source: http://www.geog.ucsb.edu/~dylan/mtpe/geosphere/topics/rx/sedimentary.html
Metamorphic Rock • Form from pre-existing igneous & sedimentary rocks • High temperatures & pressure cause the pre-existing rock to become physically or chemically altered. • Pre-existing rock becomes warped, deformed, compressed/compacted into a smaller volume of space. • They become more dense • Metamorphic rocks are less susceptible to erosion.
Examples of Metamorphic Rock… Source: http://www.geog.ucsb.edu/~dylan/mtpe/geosphere/topics/rx/metamorphic.html
Your Task • Become familiar with the three types of rocks, their characteristics and how we can identify them. • How? by completing worksheets and visiting my website. • Igneous Rocks • Sedimentary Rocks • Metamorphic Rocks