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 C

Rocks and Volcanoes

Rocks and the Rock Cycle 3

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 Rock Where 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

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. 16

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) 3/3/11

Weathering and erosion 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)

The Deadly Crystal Cave

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 

The Rock Cycle!

The rock cycle

Volcanoes

Violent eruption

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.

Volcanic Eruption on Io

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

Shield Volcano, Iceland

Kilauea HI

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

Cinder Cone Volcano

Volcanoes composite volcanoes are tall conical mountains composed of lava flows, cinders and ash in alternate layers Silica content above 52% Violent eruptions

Mt Fuji, Japan (composite volcano)

Mt St Helens, prior to 1980

Mt St Helens, after 1980

Volcanoes http://www.youtube.com/watch?v=oQEzXN3ga3g&feature=related&safety_mode=true&persist_safety_mode=1

The Ring of Fire An area where large numbers of earthquakes and violent volcanic eruptions occur in the basin of the Pacific Ocean. It is associated with a nearly continuous series of tectonic plate boundaries and movements. It has 452 volcanoes, over 75% of the world's active and dormant volcanoes. Violent volcanic eruptions

The Ring of Fire

Our local portion of the Ring of Fire

Check for understanding What effect does high silica content have on rock color? High silica, light color What effect does high silica content have on magma viscosity? High silica, high viscosity Volcanoes with high viscosity magma have ______ eruptions Violent Volcanoes with high viscosity magma have ______ Mild eruptions

Check for understanding