We began our study on rocks with a science retreat to Camano Island State Park. We observed, collected and recorded information about rocks that we found along the beach. We brought our excitement and curiosity back to the classroom and started a journey to become experts on rocks! We have been learning the characteristics of the three different types of rocks and how they are formed. We've been studying the rock cycle and are now understanding that rocks can change as they go through the rock cycle. Our vocabulary has expanded to include words such as; weathering, erosion, deposition, sediment, compaction, cementation, extrusive, igneous and lithosphere.
Crystallization: The process where solid crystals form as molten rock (magma or lava) cools.
Igneous Rock: Rocks that are formed when magma (molten rock deep within the earth) cools and hardens. Sometimes the magma cools inside the earth and other times it erupts onto the surface from volcanoes (in this case, it is called lava.) When lava cools very quickly, no crystals form and the rock looks shiny and glasslike. Sometimes gas bubble are trapped in the rock during the cooling process, leaving tiny holes and spaces in the rock. Some examples: basalt, granite, obsidian
Extrusive Igneous Rock: Igneous rocks that are formed on the surface of the earth's crust.
Instrusive Igneous Rock: Igneous rocks that are formed within the inside of the earth's mantle.
Weathering:Weathering is the breakdown of rocks at the Earth's surface, by the action of rainwater, extremes of temperature, and biological activity. It does not involve the removal of rock material and is different than erosion.
Erosion: Erosion is the process by which soil and rock particles are worn away and moved elsewhere by gravity, or by a moving transport agent such as wind, water or ice. Not to be confused with weathering.
Deposition: Deposition is the laying down of sediment carried by wind, water, or ice. Sediment can be transported as pebbles, sand and mud.
Sediment: Sediment is material deposited by water, wind or ice. Includes pebbles, sand, mud, organic remains (e.g. shells) and salts left by evaporation.
Compaction: Compaction happens when sediments are deeply buried, placing them under pressure because of the weight of overlying layers. This squashes the grains together more tightly.
Cementation: Cementation is where new minerals stick the grains together. If you were to look carefully under a microscope, you could see mineral crystals that have grown around the sediment grains and bonded them together.
Lithification: The process of sediment changing into solid rock.
Sedimentary Rock: Sedimentary rocks are formed from particles of sand, shells, pebbles and other fragments of material. Together, all these particles are called sediment. Gradually, the sediment accumulates in layers and over a long period of time hardens into rock. Generally, sedimentary rock is fairly soft and may break apart or crumble easily. You can often see sand, pebbles or stones in the rock and it is usually the only type that contains fossils. Some examples: conglomerate, limestone, sandstone
Metamorphic Rock: Metamorphic rocks are formed under the surface of the earth from the metamorphosis (change) that occurs due to intense heat and pressure (squeezing). The rocks that result from these processes often have ribbonlike layers and may have shiny crystals formed by minerals growing slowly over time on their surface. Some examples: gneiss, marble
Metamorphism: The process of chemicals, heat and pressure changing igneous and sedimentary rock into metamorphic rock.
Lithosphere:The rigid outer part of the earth, consisting of the Earth's crust and upper mantle.
Earth's Crust: The outermost layer of the Earth.
Mantle:The Earth's mantle is the thickest layer and lies between the crust and the core.
Core: The Earth's core is the part of Earth in the middle of our planet.