CEE 1030 1nd Edition Midterm Exam 1 Study Guide Lectures 1 8 Lecture 1 January 21 Introduction What are key concepts in Earth Science Earth science can be used to predict and prevent natural hazards such as earthquakes volcanoes and landslides Humans also depend on the Earth for valuable resources so we must recognize how we alter the Earth Three basic rock types Igneous cooling and solidification of magma Sedimentary weathering and layering Metamorphic changing heat and pressure Vocab terms Transform fault tectonic plates slide side by side Divergent plates move apart oceans get bigger Convergent plates collide form deep ocean trenches and mountains Lecture 2 January 23 Minerals and Resources What are the basic requirements for minerals 1 An ordered internal structure atoms are arranged in a structure 2 A specific chemical composition that may vary within a defined range 3 Naturally occurring 4 An inorganic solid How do we identify minerals Crystal form the external expression of the mineral s internal structure Luster the way in which the mineral s surface reflects the light Color the interaction of light with the mineral Streak the mineral s color in a powdered form Hardness resistance to abrasion or scratching Cleavage Fracture response of crystal to breaking cleavage is the tendency of the mineral to break along planes of weak bonding Secondary special properties shown by limited minerals ex A reaction to HCl Vocab terms Atom the smallest unit of an element Nucleus contains the mass within an atom Protons positive charges in an atom Neutrons neutral charges within an atom Electrons negative charges within an atom Isotope atoms that have a different number of neutrons than their usual state Polymorphs minerals with the same composition but different crystalline structures Lecture 3 January 28 Igneous Rocks How are igneous rocks formed Igneous rocks are formed by the solidification of magma magma is formed through the melting of rocks in the Earth s mantle As magma cools different silicate materials begin to crystallize Igneous rocks formed at the Earth s surface are extrusive rocks igneous rocks formed at a depth are intrusive rocks How does one classify igneous rocks Texture what does the rock look like What are the size of the crystals Faster cooling equals smaller crystals Types of minerals in rocs Chemical composition What are the different igneous textures Aphanitic fine grained Phaneritic coarse grained Porphyritic large crystals embedded in a matrix of smaller crystals Pegmatitic extremely coarse grained rock Pyroclastic fragmental texture Glassy very rapid cooling resulting in obsidian What minerals are in igneous rocks Silicon and oxygen are the fundamental building blocks of igneous rocks Igneous rocks can contain dark mafic silicates or light felsic silicates How does silicate content affect the viscosity of magma The more silicate in a magma the higher the viscosity This viscosity determines the kind of eruption in a volcano with lower viscosity runnier lava more gas bubbles can escape so the eruption is less explosive This is called an effusive lava flow With higher viscosity the gas bubbles are trapped as the magma rises so they eventually explode and cause an explosive eruption In order of increasing viscosity basaltic magma andesitic magma rhyolitic magma How does magma form 1 Increase temperature thermal 2 Decrease the pressure decompression 3 Add water fluid induced Lecture 4 January 30 Volcanoes and Other Igneous Activity Types of basaltic volcanoes Shield volcano a large broad circular shape with gentle dipping slopes built by successive fluid lava flows from a central vent the flows travel long distances Cinder cones scoria cones built from ejected gas rich lava fragments appear as steep slopes of loose cinders Types of intermediate rhyolitic volcanoes Composite cones stratovolcanoes classic volcano made up of interbedded lava flows and pyroclastic debris Caldera occurs when there is magma beneath the earth an eruption is triggered and the earth below the volcano collapses creating a huge basin Lava dome occurs when silicon oxygen rich lava is very viscous and thick so it is squeezed out of a vent and piles on top of itself What are some important historical volcanic eruptions Mt St Helens 1980 largest eruption in historic times in the USA the pressure of the magma in the side of the volcano caused the side to burst Mt Tambora Indonesia 1815 largest eruption in historic times caused significant weather changes Vocab terms Lava flows non explosive eruptions Pyroclastic deposits explosive eruptions Pahoehoe flow ropy textured lava with higher temperature and less viscosity Aa flow rough blocky lava that results from a loss of gas and temperature increased viscosity Submarine eruptions lava eruptions under water at mid ocean ridges Pyroclastic flows a fluidized mix of semi solid rock fragments and hot expanding gases that flow down a volcano flank Pyroclastic material fragmentation of magma and rock Lahars volcanic mud flows from a mixture of volcanic debris and water Dike a tabular intrusion in layers of rock that cuts across the layers Sill a tabular intrusion in layers of rock that cuts parallel to the layers Batholith large intrusions in rock Lecture 5 February 4 Weathering and Soils What are Earth s external processes Erosion is the first step toward breaking down rocks it is the physical removal of material by mobile agents such as wind or water The next step is weathering which is the process of breaking down through disintegration or chemically altering through decomposition of rock at Earth s surface These processes lead to the formation of sedimentary rock What are the different kinds of mechanical weathering Frost weathering when water gets into cracks of rocks and freezes it expands and breaks rocks further apart Root wedging tree roots grow into cracks of rocks and force them apart Salt wedging the evaporation of water leads to the growth of salt crystals in rock cracks further wedging them apart Thermal expansion daily temperature changes causes expansion in rocks Unloading taking off layers of rock lessens the pressure on underlying rocks creates expansion and exfoliation sheets What are the different kinds of chemical weathering Dissolution promoted by acidic water Hydrolysis reaction of minerals with water Oxidation exposure to oxygen What affects the rate of chemical weathering A greater surface area of a rock means a rock will weather