CEE 1030 1nd Edition Midterm Exam 2 Study Guide Lectures 9 18 Lecture 9 February 20 Geologic Time 2 What are the different parts of an atom Within the nucleus there are protons which make up the atomic number neutrons protons and neutrons constitute the mass number and electrons Isotopes are elements with a nonstandard number of neutrons What is radioactive decay How do we use it in geology Radioactive decay occurs when there are changes in the structure of an unstable atomic nuclei The parent is the original isotope and the isotopes resulting from the decay are called daughter products We can use radioactive decay to determine how old certain rocks are What are the methods of radioactive dating Carbon 14 Radiocarbon Dating can date materials with carbon in them up to several thousand years old Uranium Lead Dating is also useful Lecture 10 February 26 Structural Geology Why is structural geology important Structural geology is the study of rocks and their geometry which is useful in determining where it is safe to build roads and buildings Scientists can use aerial photography satellite imagery and GPS to study and predict patterns and hazards caused by plate tectonics What is deformation Deformation is the general term for all changes in the original form or size of a rock unit Elastic deformation occurs when the rock returns to its original size and shape when stress is removed whereas brittle deformation occurs when the rock fractures Rock deformation can come about based on temperature confining pressure rock minerals and time What are the types of faults Dip slip fault the movement is parallel to the fault s surface Normal dip slip faults accommodate the lengthening or extension of the crust Reverse and thrust dip slip faults accommodate the shortening of the crust Strike slip fault the dominant displacement is horizontal and parallel Vocab terms Strike trend the compass direction of the line produced by the intersection of an inclined rock layer or fault with a horizontal plane Dip inclination the angle of inclination of the surface of a rock unit or fault measured from a horizontal plane Stress the force applied to a particular area Strain the change in a rock s shape or size due to stress Joint a type of rock fracture where there is no movement across the crack Fault a type of rock fracture where there is movement of the rocks on either side of the crack Hanging wall the rock surface above a fault Footwall the rock surface below the fault Syncline a type of fold in the shape of a U Anticline a type of fold in the shape of an A Monocline a large step like fold in an otherwise horizontal sedimentary strata Dome an anticlinal structure where the oldest rocks are in the center Basin a synclinal structure where the youngest rocks are in the center Lecture 11 February 27 Earthquakes What is an earthquake An earthquake is a sudden release of energy accumulated in deformed rocks which radiates as seismic waves Earthquakes are studied by seismologists who use seismographs to record seismic activity What are the different kinds of seismic waves Surface waves travel over the Earth s exterior categorized by side to side love waves and upand down Rayleigh waves Body waves travel through the Earth s interior categorized by pushpull Primary waves and shaking Secondary waves Where are earthquakes found and how do they affect us Earthquakes are focused around plate margins Predicting earthquakes is tricky but one way to do so is to map out earthquake occurrences and search for gaps in the plate boundary The extent of damage caused by an earthquake depends on depth of the earthquake the intensity and duration of vibrations the nature of material the structure rests on the design of the structure and the quality of construction Earthquakes can also trigger tsunamis through the movement of a surface fault or landslide How are earthquakes measured Generally earthquakes are measured using the Richter Scale which is based on the amplitude of the largest seismic wave recorded and adjusted from the distance to the epicenter Each unit of Richter magnitude increase corresponds to a tenfold increase in wave amplitude and a 32fold energy increase Intensity is the measure of the degree of shaking at a given locale based on the damage done Magnitude is an estimate of the amount of energy released at the source of an earthquake Vocab terms Focus the site of initial rupture that causes an earthquake Epicenter the point directly above the focus Potential test questions What kind of a fault is the San Andreas Fault Strike slip fault Lecture 12 March 4 Plate Tectonics What are plate tectonics Plate tectonics have shaped much of the Earth sciences Plate tectonics explain the movement of continents across the Earth s surface Due to the presence of similar fossils on different continents and the clusters of similar rocks between continents scientists have determined that our current continents have split from an original supercontinent Pangaea What are the three types of plate boundaries A transform boundary occurs when plates slide past one another A divergent boundary occurs with seafloor spreading when two plates move apart from one another This creates new oceanic crust When the continental crust splits at a rift it can lead to the creation of new ocean A convergent boundary occurs when plates collide therefore creating new ocean lithosphere What drives plate motions Plate tectonics are a response to the cooling of the Earth and thermal convection in the solid mantle Vocab terms Lithosphere the outer rigid shell of the Earth Asthenosphere the weak ductile mantle below the lithosphere Slab pull the sinking of dense oceanic lithospheric slab Mantle plumes rising plumes of hotter mantle material that is stationary involved with the creation of volcano chains Potential test questions How much to tectonic plates move per year Approximately 10 cm year Lecture 13 March 6 Earth s Interior How do we calculate the density of the Earth Because the average density of the Earth is greater than the densities of both the crust and the mantle the center of the Earth must be more dense than both We can also use seismology to study the interior of the Earth P waves can be transmitted through liquid and solids whereas S waves cannot be transmitted through liquid S waves therefore bounce off of the Earth s inner core What are the different layers of Earth s interior The core an iron rich sphere containing the solid inner