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Chapter 1: Dynamic Earth
• Geology is defined as the study of earth
o This is broken up into physical geology and historical geology. Physical Geology – studies earth materials such as minerals and rocks, as well as the processes that operate within Earth and on its surface.
Historical Geology – examines the origin and evolution of earth, its continents, oceans, atmosphere, and life.
• One of the greatest environmental issues is over-population. We are coming up on 7 billion and all these people need to be clothed, fed, and housed.
• Another hot issue is global warming, carbon dioxide gases are the major cause of this. The industrial revolution was also the spawn of global warming. Deforestation in the tropics is devastating because the trees help recycle our carbon dioxide.
o Glaciers melt due to warming temps, which increases the water level.
• The earth consists of three concentric layers and are different densities (listed from most to least dense): the core, mantle, and crust
o The core occupies about 16% of the earth’s total volume. The inner core is solid and the outer core is liquid (seismic waves).
o The mantle makes up about 83% of earth’s volume. The asthenosphere surrounds the mantle and spawns magma. The solid portion of the upper mantle is the lithosphere, which is broken into plates that move (plate tectonics).
o The crust is the outermost, exposed surface of the earth. It has two types however, oceanic and continental crust. Oceanic crust is denser.
• Scientific method is an orderly, logical approach that involves gathering and analyzing the facts or data about the problem under consideration. Then, hypotheses are formulated to explain the observed phenomena.
• According to plate tectonic theory, the lithosphere is composed of different plates that move over the asthenosphere. Plate boundaries are mostly marked by volcanic activity or earthquake activity. These plates move in three different ways:
o Divergent plates move apart as magma rises to the surface and are recognized by linear rift valleys.
o Convergent plates are when one plate sinks beneath another plate (subduction zone). The sinking plate is heated up and melted to form magma, volcanoes are an indicator of a subduction zone.
o Transform plates are sites where the plates slide sideways. An example is the San Andreas Fault in Cali. This is the site of countless earthquake activity.
• It is also theorized that all the plates were once connected to form a “supercontinent” called Pangaea. 
• There are three principle rock types: igneous, sedimentary, and metamorphic.
o Igneous rocks result from magma crystallizing. This rock type is categorized further into intrusive and extrusive. Intrusive is when it is formed underground and extrusive is formed on the surface of earth.
o Sedimentary rocks are collections of sediments from the weathering of rocks exposed to wind, water, glaciers, etc all cemented (lithified) together. There are three ways for these rocks to form: solidation of rock fragments, precipitation of mineral matter from solution, or compaction of plant or animal remains. These rocks are very useful for interpreting earth history because of their formation on the surface.
o Metamorphic rocks are usually formed beneath the surface from the alteration of other rocks by heat, pressure, and chemical activity. An example is marble.
• Heating within the earth’s interior results in convection cells that power the movement of plates.
• The principle of uniformitarianism is based on the premise that present-day processes have operated throughout geologic time.

Chapter 2 – Plate Tectonics
• Continental drift is the idea that the continents are moving on plates and were broken puzzle pieces of Pangaea.
• The Curie point is the temperature at which the magnetic poles in minerals lay still. So when magma is cooled, it records the position of the poles at that point in time. The study of this is called Paleomagnetism. It can be interpreted from these rocks that the poles moved, the continents moved, or both. The best explanation is the plates moved and so reinforces the theory of continental drift.
• It has been shown that the earth’s polarities have completely switched during the past (magnetic reversals).
• Another theory for the moving of the plates is seafloor spreading. The theory suggests the seafloor separates at oceanic ridges were new crust is formed from rising magma. Thermal convection cells are said to drive this engine and reinforcing this theory is the fact oceanic crust is younger then 180 million years old and continental crust is 3.96 billion years old.
• Plate tectonic theory revolves around the heat-transfer system under earth’s surface that causes the plates to move over the asthenosphere. Evidence for this theory is overwhelming and so is widely accepted as the “right” theory. This theory supports mountain building, earthquake activity, and volcanism.
• Oceanic crust is the only one that is subducted into the earth.

Chapter 3 – Minerals
• A mineral is a naturally occurring, inorganic, crystalline solid, with a narrowly defined chemical composition and characteristic physical properties.
o “Naturally occurring” excludes all substances made by humans; geologists disregard all synthetic diamonds or rubies. Corals and clams make their shells of aragonite or calcite, both of which are minerals.
o “Crystalline solid” means a solid in which the atoms are arranged in a regular, three dimensional framework.
• All matter is made of chemical elements, each of which is composed of atoms. Atoms are the smallest particle and cannot be split. The number of protons in an atoms nucleus determines the atom’s identity and its atomic number. Atoms are also characterized by their atomic mass number, the sum of protons and neutrons in the nucleus.  
o Two of the same element can have a different atomic number. For example a Carbon atom has 6 protons always, but the number of neutrons can be 12, 13, or 14. We recognize three different types of Carbon called isotopes, each with a different atomic mass number. Some isotopes are radioactive such as carbon 14, but carbon 12 and 13 are both stable.
• An atom such as chlorine has 17 protons and 17 electrons so it is electrically neutral. If one of the electrons were to “drop out” it would have fewer electrons than protons, so it is an electrically charged ion given the symbol Na+1.
o Electrons – negatively charged
o Protons – positively charged
o Neutrons – neutral
• Van der Waals bonds are a weak attractive force that bonds atoms together but flakes off easily. An example is pencil lead flakes off onto the paper as it glides over the page.
• Cleavage is a term to describe a characteristic of certain minerals that allows them to split along smooth planar surfaces.
• Silicate minerals make up about 95% of earth’s crust. These are minerals that are composed of silicon and oxygen. These minerals are made from a silica tetrahedron, consisting of four oxygen atoms surrounding one silicon atom to form a four-faced pyramid. There are two main subgroups of silicates:
o Ferromagnesian silicates contain iron, magnesium, or both. These silicates tend to be dark and more dense than nonferromagnesian silicates.
o Nonferromagnesian silicates lack iron and magnesium and tend to be light colored and less dense. Feldspar is the most common mineral in this group and is abundant on earth’s surface.
• Mineral identification examines physical properties to get an idea of the chemical compound for the mineral:
o Color and luster: color is obviously the color of the rock but this can sometimes be different from the color left from scratching it on another rock. Luster is the appearance in reflected light broken down into: metallic and nonmetallic. Nonmetallic luster can be further broken down into glassy, vitreous, greasy, waxy, brilliant, dull, and earthy.
o Crystal form: minerals form in different ways depending on their chemical compounds. NaCl, for example, can form into cubes.
o Cleavage and fracture: minerals can have up to six directions of cleavage. A diamond has four directions and even though it is the hardest mineral, it can be cleaved rather easily if the lines of cleavage are obeyed. Fracture surfaces are rugged breaks that happen when a given amount of pressure is applied to the mineral.
o Hardness: this is a scale from one to ten, ten being the hardest, for minerals. A diamond is ten because it is the hardest mineral. The values can be determined depending on what minerals can scratch them.
o Specific gravity: this is the ratio of its weight to the weight of an equal volume of water. If a mineral has a specific gravity of 3, it is 3 times as heavy as water.  
• A resource is a naturally occurring solid, liquid, or gas material in or on Earth’s crust and is economically feasible to extract. A reserve is the amount of the resource that is economically feasible.

Chapter 4 – Igneous Rocks and Intrusive Igneous Activity
• Magma is molten rock below the surface and lava is simply above the surface. This material is usually cooled below the surface or ejected out forcefully in pyroclastic flows.
• All igneous rocks are derived from magma. When igneous rocks are cooled above the surface, they make volcanic or extrusive plutonic rocks. Cooled magma below the surface is called plutonic or intrusive igneous rocks.
• Magma is separated into three groups:
o Felsic magma is silica rich and tend to be involved in extremely explosive eruptions.
o Mafic magma is silica poor but contains more calcium, iron, and magnesium.
o Intermediate magma is obviously between the two.
• Since rocks are poor conductors, lava can stay hot for months or even years.  
• Viscosity is the resistance to flow. If lava has low viscosity levels, it will flow quickly. Mafic lava has lower silica and so will move more quickly than Felsic.
• Felsic lava tends to not reach the surface as frequently as mafic lava because of its high silica levels so it moves slowly.
• Magmas formed below spreading ridges are generally mafic but the upper mantle rocks are considered to be ultramafic.
• When magma is cooled very rapidly, it forms a very fine grained texture in which individual minerals are too small to be seen without magnification called aphanitic texture. If magma cools so fast that the atoms don’t have time to be ordered in their three dimensional framework, obsidian (natural glass) forms.
• Some lava contains large amounts of water vapor and form rocks with vesicles, holes, when cooled.
• Plutons are formed when magma cools and crystallizes within the crust therefore; we can only observe these after erosion has exposed them to the surface. Plutons are separated into two groups:
o Dikes have boundaries that cut across perpendicular to the bed rock and form where fractures exist or weak spots in the rocks.
o Sills are parallel to the rocks are formed when the magma pressure is so great that it actually lifts the overlying rocks. Because they lift the earth, sills tend to be closer to the surface because they have to build pressure that overcomes the weight above it.
? Laccoliths are similar to sills but instead of being flat, they form a more hill or “mushroom” shape on the surface.
• The volcanic pipe is the path way the magma takes to the surface. When a volcano erodes, it leaves the volcanic pipe extruding from the surface called a volcanic neck.
• A Batholith is the largest of all plutons and must have at least 100 km^2 of surface are.

Chapter 5 – Volcanism and Volcanoes
• Volcanism is the process of which magma is ejected into the atmosphere.
• Most of all volcanic gases are comprised mainly of water vapor.
• Sometimes lava form a passage way called a lava tube which allows lava to travel as fast as 50 km/h because it insulates the sides and creates a sort of low friction slide.
• Pillow lava is formed when lava is cooled very quickly underwater and forms pillow shaped igneous rocks.
• Ash is also ejected along with lava and can clog a lot machinery.
• Since volcanoes extract magma from under the earth, a crater is sometimes formed in front of volcanoes.
• There are several different types of volcanoes:
o Shield volcanoes resemble a shield lying on the ground with gently sloping sides. These volcanoes are quiet and gentle when compared to other types of volcanoes. These account for about 99% of the volcanoes in Hawaii.
o Cinder cones are short lived, but fast growing volcanoes. Sometimes they can spark from the ground and reach 100 m in two days. They are made of pure pyroclastic materials so don’t tend to be more than 400 m due to the awkward shapes of the hardened materials
o Composite volcanoes or stratovolcanoes are made of pyroclastic layers and lava flows. When it rains a lot on these layers, they create mud slides called lahars that can build up and destroy buildings. These volcanoes are the typical extremely large volcanoes and can be a very dangerous threat.
o Lava domes are steep-sided and are composed of felsic lavas and so grow very slowly due to the viscous lava. These volcanoes are generally extremely explosive and can cause a dense cloud of pyroclastic materials racing down the mountain at extreme speeds, called a nuee ardente.
o Fissure eruptions are when cracks in the ground allow very fluid (low viscosity) flows that simply spread out over the top layer and formed a basalt plateau.
• Volcanic activity is measured with the volcanic explosivity index (VEI) and is semiquantitative. It gives scores from 0 to 8 based on the volume of the ejected materials and the height of the eruption plume but not the number of fatalities or damage caused.
• Predicting eruptions is very difficult because many (42%) have their massive eruption on their first day of showing volcanic activity while others may take months or years. Volcanic tremors are an indicator to and explosion because they are caused by magma moving under the surface.
• Most volcanoes are on the circum-Pacific belt (60%), the Mediterranean belt (20%), and the rest are along plate boundaries.

Chapter 6 – Weathering, Erosion, and Soil
• Mechanical weathering is when physical forces break materials into smaller parts but they still retain their chemical composition. This can be done in many ways:
o Frost Action is when water repeatedly freezes and seeps into cracks and separates materials
o Pressure release happens when rocks are formed underground with high pressure and then are exposed at the surface due to erosion. The rapid drop in pressure causes the rocks to expand.  
o Thermal expansion as temperatures heat up and cool down, rocks expand and contract. Since rock is a bad conductor, the outside part of the rock may expand while the inner rock does not and cause it to fracture.
o Organisms cause weathering as well. Animals that burrow mix different sediments and tree roots and grow and break other rocks.
• Chemical weathering is a process which the different types of weathering alters the chemical composition of the materials. Important agents in these processes include atmospheric gases (oxygen), water, and acids.
o During Solution the ions of substance separate in a liquid and the solid substances dissolve. Many substances cannot be dissolved in pure water but when acid is added like CO2, it can soon dissolve many substances rather quickly.
o Oxidation is the reactions with oxygen to form an oxide. An example would be a metal combining with oxygen to form rust.
o Hydrolysis is a chemical reaction between the hydrogen ions and hydroxyl ions of water. The hydrogen atoms actually replace positive ions in materials therefore changing their chemical characteristics.
• Leaching is a process where water percolating through the soil brings dissolved minerals down with it to lower levels of soil. The soil is separated into different layers called soil horizons. The zone of accumulation collects all the dissolved minerals.