Geol 101 Physical Geology PAST EXAM QUESTIONS LECTURE 4 PLATE TECTONICS II 4 Which of the following statements about paleomagnetism at spreading ridges is FALSE A there is a clear pattern of paleomagnetic properties in seafloor rocks that formed at spreading centers B rocks formed at spreading ridges preserve paleomagnetic signals that repeatedly reverse through time C the paleomagnetic pattern on one side of a ridge is very different to that on the other side of the ridge D lavas erupting at mid ocean ridges today would preserve a positive polarity in the magnetic signal E the paleomagnetic stripes in the ocean floor rocks run parallel to the spreading ridge 4 Which of these statements about paleomagnetism as determined from a study of spreading ridges is FALSE A there is a clear paleomagnetic signal in rocks to either side of a spreading ridge B rocks along spreading ridges all show normal polarity no matter what their age C the paleomagnetic pattern on one side of a ridge is a mirror image of that on the other side of the ridge D there is evidence that Earth s magnetic poles reverse approximately every half million years E all the world s spreading ridges show evidence of paleomagnetic reversals in the adjacent ocean rocks 4 Which of the following statements about paleomagnetism at spreading ridges is TRUE A there is no clear paleomagnetic signal in rocks at spreading ridges B rocks along spreading ridges show the same paleomagnetic north no matter what their age C the paleomagnetic pattern on one side of a ridge is the mirror image of the other side of the ridge D there is evidence that Earth s magnetic poles reverse every 11 years or so E the paleomagnetic characteristics of rocks next to spreading ridges are still unknown 4 We see bands of oceanic crustal rocks alongside mid ocean ridges with alternating magnetic polarity paleomagnetism because A seafloor spreading occurs at mid ocean ridges B Earth s magnetic field reverses about every half million years C plate tectonics causes continents and ocean crust to slowly drift away from ridges D new ocean crust is constantly being created at mid ocean ridges E all of the above 4 The age of the oldest oceanic crust in any of the world s oceans is A 4600 million years B 1200 million years C 500 million years D 180 million years E 70 million years 4 The mid Atlantic ridge is an example of a spreading ridge As a result of the process of 1 that occurs at this ridge the youngest oceanic crust in the north Atlantic must be located 2 A 1 seafloor spreading 2 along the ridge itself B 1 seafloor spreading 2 along the coasts of N America and Europe C 1 seafloor spreading 2 with a striped pattern of repeating old and young rocks D 1 subduction 2 along the ridge itself E 1 subduction 2 along the coasts of N America and Europe 1 4 The mid Atlantic ridge is an example of a spreading ridge As a result of the process of 1 that occurs at this ridge the oldest oceanic crust in the north Atlantic must be located 2 A 1 seafloor spreading 2 along the ridge itself B 1 seafloor spreading 2 along the coasts of N America and Europe C 1 seafloor spreading 2 with a striped pattern of repeating old and young rocks D 1 subduction 2 along the ridge itself E 1 subduction 2 along the coasts of N America and Europe 4 As a result of seafloor spreading at a mid ocean ridge the following is true A rocks on one side of the ridge have the opposite magnetic polarity to the other side B Earth s magnetic field reverses about every half million years C older oceanic crust is slowly pushed away from ridge D continents plow through the oceanic crust E all of the above 4 The oldest oceanic crust occurs 1 and the youngest occurs 2 A 1 at mid ocean ridges 2 along subduction zones B 1 at mid ocean ridges 2 along the continental margins C 1 along the continental margins 2 at mid ocean ridges D 1 along the continental margins 2 along subduction zones E 1 somewhere beneath the continental slope 2 at mid ocean ridges 4 As a result of seafloor spreading A new ocean crust is generated at ridges to accommodate the spreading plates B continents attached to the plates on each side of the ridge slowly move apart C the age of ocean crust increases with increasing distance away from the ridge D a record of paleomagnetic reversals is recorded in rocks that formed at the ridge E all of the above 4 If you were to collect samples at the following locations along the sea floor of the North Atlantic ocean which sample of rock would be the oldest A along the spreading ridge B where the spreading ridge comes ashore in Iceland C just east of the spreading ridge D just west of the spreading ridge E just off the coast of North America 4 Tectonic plates are not very thick compared to the radius of the Earth because they are only made up of rocks that are part of the A ocean crust B continental crust C lithosphere D asthenosphere E mantle 4 Tectonic plates are made up of 1 that floats on the underlying 2 A 1 basalt 2 gabbro B 1 lithosphere 2 asthenosphere C 1 continental crust 2 mantle D 1 continental and oceanic crust 2 lithosphere E 1 lithosphere 2 outer core 2 4 The fastest plate motion velocity that has been measured anywhere on Earth is 18 cm yr which occurs at the A San Andreas fault B mid Atlantic ridge C East Pacific Rise D Juan de Fuca spreading ridge E Aleutian subduction zone 4 The fastest moving mid ocean ridge spreading center is A the mid Atlantic ridge B the East Pacific Rise C the Juan de Fuca ridge D the Cascadia subduction zone E the Himalayas 4 What type of plate boundary is represented by a mid ocean spreading ridge A divergent B convergent C transform D subduction E strike slip 4 The three types of tectonic plate boundaries are A normal reverse and strike slip B active passive and extinct C divergent convergent and transform D seismic volcanic and subducting E ocean ocean ocean continent and continent continent 4 Which of the following combinations is a correct match between 1 a type of plate boundary and 2 a geographic example of that type of plate boundary A 1 divergent 2 San Andreas fault B 1 convergent 2 Red Sea C 1 transform 2 Japan D 1 transform 2 Himalayas E 1 divergent 2 East African Rift Valley 4 Which of the following combinations is a correct match between 1 a type of plate boundary and 2 a characteristic feature of that type of plate boundary A 1 divergent 2 subduction zone B 1 convergent 2 transform fault C 1 transform 2 subduction zone D 1 transform 2 island arc E