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For the food chain shown, which of the following changes would have the most severe consequences? A a drastic decrease in rainfall, causing drought B the poaching of predatory hawks by game hunters C the introduction of a second predator that eats field mice
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For the food chain shown, which of the following changes would have the most severe consequences? A a drastic decrease in rainfall, causing drought B the poaching of predatory hawks by game hunters C the introduction of a second predator that eats field mice D a parasitic infestation that reduces the cricket population
Earth’s Rocks and the Rock Cycle • Rocks can be found everywhere on Earth. Rocks are a naturally occurring solid mixture of minerals and (sometimes) organic materials. • Rocks are classified by • mineral and chemical composition • texture of the particles • and also by the processes that formed them.
Igneous sedimentary metamorphic
Igneous Rocks • Formed from lava or magma (Both are molten rock) • Magma= underground • Lava = above ground • Types of igneous rock • Intrusive: form when magma cools • Large crystals (coarse-grained) • Extrusive (Volcanic): form when lava cools • Small crystals (fine-grained) • Think: Why are the crystal sizes different?
Igneous RockWhere does Igneous Rock come from? • crystallize from cooling magma
Intrusive Igneous Rock • Rocks form from magma cooling beneath Earths surface • Coarse grained • Large crystals form and grow • Takes a long time to cool and harden • e.g. granite
Extrusive Igneous rocks • Forms from magma that is brought to Earths surface (lava) • Lava cools more rapidly so large crystals do not have time to form • Fine grained • e.g. Obsidian, pumice
Color of Igneous Rock • Rocks high in silica are lighter in color • Rocks low in silica are darker in color • Silica- • A chemical compound that is the main constituent of most of the Earth's rocks. • the main chemical compound in sand. • Silica is used to make glass, concrete, and other materials.
Check for understanding • What is molten rock below the surface? • What is molten rock above the surface? • What type of rock forms from magma? • What type of rock forms from lava? • What can you assume about the composition about a light colored sample of igneous rock?
Check for understanding Fine grained igneous rock has _____ crystals. Small crystals form in ______ igneous rock. Coarse grained igneous rock has ___ crystals. Large crystals form in ______ igneous rock.
Which of the following atoms has the largest atomic radius? A barium (Ba) B chlorine (Cl) C iodine (I) D magnesium (Mg) Which of the following atoms has six valence electrons? A magnesium (Mg) B silicon (Si) C sulfur (S) D argon (Ar)
Weathering and erosion • Weathering • Mechanical: physical breaking of rock by abiotic means (e.g. ice expanding in cracks) • Chemical: rock dissolved by acids • Biological: plants breaking rock with their roots • Erosion: movement of dissolved or fragmented rock • Deposition: rock material comes out of solution or suspension
Sedimentary rocks (rock on!) • formed from compressed or cemented layers of sediment • Types • Clastic: formed from pieces of other rocks that are glued together. (e.g. Sandstone) • Chemical: formed by precipitation of elements dissolved in water (e.g. rock salt, limestone) • Organic:formed from remains of living things (e.g. coal)
Check for understanding • How is sedimentary rock formed? • What type of sedimentary rock is formed from the remains of living things? • How is rock broken down? • What type of sedimentary rock is formed from small rocks that are stuck together? • What type of sedimentary rock is formed when chemicals precipitate out of solution?
Metamorphic Rock • A rock that forms from other rocks as a result of intense heat, pressure, or chemical processes. • There are two basic types of metamorphic rocks: • 1) foliated metamorphic rocks such as gneiss and slate which have a layered or banded appearance • 2) non-foliated metamorphic rocks such as marble which do not have a layered or banded appearance.
Metamorphic Rock • Some examples: • Limestone marble • shale slate
Volcanoes • What is lava? • How does molten rock get to the surface? • Volcano: an opening in a planet's surface or crust, which allows hot magma, volcanic ash and gases to escape from below the surface. • Extrusive igneous rock is also known as “volcanic”
Viscosity is a measure of the resistance of a fluid • viscosity is "thickness" or "internal friction". • water is "thin", having a lower viscosity • honey is "thick", having a higher viscosity. • The less viscous the fluid is, the greater its ease of movement
Volcanoes there are two kinds of volcanoes: ones with violent eruptions producing steep slopes and ones with voluminous lava flows producing gentle slopes.
Volcanoes Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent, but not generally explode catastrophically. low-viscosity magma is typically low in silica (<52%), but high in Magnesium and Iron (e.g. The Hawaiian islands) Mild eruptions
The size of Olympus Mons is so great (roughly the size of Missouri) that a person standing on the surface of Mars would be unable to view the profile of the volcano. The only way to view the mountain properly is from orbit.
Volcanoes cinder cones are the result from eruptions that erupt mostly small pieces of pyroclast that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 meters high. Silica content above 52% High viscosity magma Violent eruptions
Volcanoes composite volcanoes are tall conical mountains composed of lava flows, cinders and ash in alternate layers Silica content above 52% Violent eruptions
