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Asynchronous Plate Tectonics Lab developed for Teach the Earth Module 2: Discovering Plate Boundaries Student Worksheet Introduction The Theory of Plate Tectonics was developed in the mid-20 th century and continues to be refined today. This is an excellent example of the process of science in action. In this module, you will use real data to locate the boundaries between plates and define the types of boundaries, just as scientists do. There are two activities in this module. This module should take 2 hours to complete. Learning Objectives ● Learn the locations and names of the major and minor lithospheric plates. ● Recognize the boundary types that define each plate. ● Explain the geologic phenomena associated with each type of boundary. ● Describe the relative motion of the plates and the data that support this description. ● Apply knowledge of plate boundaries, and their consequences, to create an internal image of a part of Earth’s anatomy. Background This is an inquiry-based activity, which means that prior knowledge is not required. The process of science requires that observations be made before any interpretations are made. Observations are key to the development of any theory. The Theory of Plate Tectonics was developed using the same data you will examine here. As you make more observations, your interpretations will be refined and your understanding will deepen. As you work through this activity, you will follow a path similar to that of the many hundreds of scientists who discovered the plates, and came to understand how the actions at plate boundaries give rise to features on Earth’s surface and below. That path often includes gaps and missteps. Science does not progress in a straight line and these missteps are part of the process. The more we learn the better we can explain and interpret. Plate Boundaries The following is a summary of plate boundaries. You can also find block diagrams of these boundaries below in Lab Activity 2. Divergent Boundary Where plates separate, mantle material rises up as magma, producing new crust by volcanic activity. These are termed spreading centers. Mid-ocean ridges are the most common manifestation; where a continent is being pulled apart, large graben or rifts are formed until an ocean basin opens up (or not). Convergent Boundary Moving plates inevitably run onto one another as they are pushed away from sites of new crustal formation. Oceanic trenches mark lines of collision between oceanic and continental masses, resulting in volcanic mountain chains above the subduction plate Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson

Asynchronous Plate Tectonics Lab developed for Teach the Earth ( volcanic arcs ) and non-volcanic (structural) mountain chains that result from the collision impact of one continental mass against another. Transform Boundary Where adjacent plates are moving past each other, or in the same general direction but at a different velocity, the feature produced is a transform fault , which is a strike-slip fault. Transform plate boundaries can cut through continents, or across spreading centers. Lab Activity 1: Discovering Plate Boundaries In this activity, we will look at actual scientific data that support the Theory of Plate Tectonics in order to create a synthesis map of the world that includes 1) the boundaries between plates, 2) location of named plates, 3) direction of relative movement of the plates, and the 4) location of hot spot volcanoes (those not related to plate boundaries). There is no perfect map and your result may be different than anyone else’s. Observations of Scientific Data Download Plate Boundary Data Maps A through F. Printing is optional. If a printer is available, it can be useful to print the maps, overlay them two at a time on a window during daylight hours. 1. Examine data maps A through E carefully. Write your observations for each map below. Avoid using scientific terminology or making interpretations. The type of data on each map is different. For the point data (such as volcanoes and earthquakes), look for distribution patterns. For surface data (topography, heat flow, seafloor age), look for where the surface is high and where it is low, where it is old and where it is young, etc. Some questions that might be asked: What sort of data are you looking at (point or surface)? What do the different colors indicate, what are the units used, and what are the ranges in values? What are some examples of extreme data points/locations? What are some patterns in the data? Where are the data uniform or consistent over a large area and where is it highly varied? Map Type Data Observations Map A: Earthquakes Type answer here: Map B: Age of the Ocean Crust Type answer here: Map C: Volcanoes Type answer here: Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson

Asynchronous Plate Tectonics Lab developed for Teach the Earth Map D: Heat Flow Type answer here: Map E: Bathymetry and Topography Type answer here: Interpretation of Scientific Data 2. Using your observations, your text, the USGS dynamic planet map found at the following link: Dynamic Planet and any other source you can find (provide a citation), create a plate tectonics summary map by following the steps outlined below. For reference, detailed descriptions of the data shown on maps A through E can be found at the bottom of the lab in the Appendix. This map may be drawn by hand or with a digital drawing program. Not all plate boundaries match exactly. There may be gaps between the boundaries where data are scarce. That is OK and to be expected. Interpretations of data can and will differ. ● Print or download base Map F. You will be making your annotations and drawings on this map. ● Locate the major plate boundaries and, using your data observations and sources, color the boundaries for the 9 major plates and 6 minor plates listed in the table below (ignore micro-plates) by identifying the type of boundary surrounding each plate. Color the plate boundaries using the color scheme described below. Please use colors as close to these as possible. Figure 1 Arrow types for different plate boundaries ● Add arrows indicating relative motion in several places along the boundary. ● Add a legend to your map indicating boundary types and symbols. ● Clearly, and in big letters (so that they can be read at a distance) label each Plate in black . The North American Plate is done as an example. You may also choose to color each individual plate (optional), but be neat - if it can’t be read, it can’t be graded. Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson

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Asynchronous Plate Tectonics Lab developed for Teach the Earth Major Plates Minor Plates African Plate Arabian Plate Antarctic Plate Caribbean Plate Australian Plate* Cocos Plate Eurasian Plate Juan de Fuca Plate Indian Plate* Philippine Plate Nazca Plate Scotia Plate North American Plate Pacific Plate South American Plate *These can also be interpreted as two separate plates. ● Use the map of prominent volcanic hotspots below and add them to your map as moderate circles in purple . Figure 2 Global map with selected hotspots 3. Summarize your findings by filling out the table below. Be sure to address each of the following in your discussion. The first two (the African and Antarctic Plates) are done as examples. a. Identify and describe the boundary types that define each major and minor plate. b. List the geologic phenomena (earthquakes and faults, volcanoes, trenches, or mountains) associated with each type of boundary. c. Describe the motion of each plate relative to its neighboring plates, and provide the observation that supports this description. Plates Boundary Types, Geologic Phenomena, Relative Motion African Plate The African Plate is nearly surrounded by divergent boundaries, with only a small convergent boundary on the northside, and Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson

Asynchronous Plate Tectonics Lab developed for Teach the Earth possibly a transform boundary connecting that to the divergent boundary on the eastern side of the plate. There are volcanoes and shallow earthquakes along all of the divergent boundaries, but none are above sea level. The northern convergent boundary has created the Alps Mountain range north of the Mediterranean Sea. There are many earthquakes and active volcanoes along this boundary as well. The African Plate is moving northward into the Eurasian Plate, and away from S. America, Antarctica and Australian Plates. Antarctic Plate The Antarctic Plate is surrounded by divergent boundaries that are tied together with transform boundaries, the most extensive of which connects it to the S. American plate. The Antarctic Plate is essentially staying put while all of the surrounding plates move away from it. Arabian Plate Type answer here: Australian Plate Type answer here: Eurasian Plate Type answer here: Indian Plate Type answer here: Nazca Plate Type answer here: North American Plate Type answer here: South American Plate Type answer here: Caribbean Plate Type answer here: Cocos Plate Type answer here: Juan de Fuca Plate Type answer here: Pacific Plate Type answer here: Philippine Plate Type answer here: Scotia Plate Type answer here: Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson

Asynchronous Plate Tectonics Lab developed for Teach the Earth Lab Activity 2: Below the Surface of Plate Boundaries On the map below there are six boxes labeled 1-6. In this activity you will match each defined region to the cross section that shows what the plate boundary looks like below the surface. Feel free to access the online textbook found at this link as an additional resource. Figure 3 Global map labeled with focus areas of interest 4. Examine the cross sections of different plate boundaries below. For each numbered focus area (rectangle) on the map above, write the name of the boundary type that represents the geology of that area in the table below. Note that there are six focus areas and five cross sections. At least one cross section will be repeated while others may not represent any of the focus areas. Focus Area Plate Boundary Cross Section 1 Type answer here: 2 Type answer here: 3 Type answer here: 4 Type answer here: 5 Type answer here: 6 Type answer here: Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson

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Asynchronous Plate Tectonics Lab developed for Teach the Earth Appendix: Plate Boundary Data Maps Descriptions Map A: Earthquakes This map shows earthquake locations and depths. The location of each earthquake is indicated by a small dot and its depth is indicated by the color of the dot. Shallow earthquakes (0 – 12 km) are white, with graduated greys down to 400 km. Earthquakes over 400 km in depth are represented by black dots. Earthquake magnitude is not shown on this map however, all earthquakes shown are of a Richter magnitude of 4 or greater. These data were obtained from the Advanced National Seismic System (ANSS) maintained by the U.S. Geological Survey and its global partners. Map B: Age of the Ocean Crust The colors represent the age of the oceanic crust . There is a color bar on the left side of the map that shows the ages in millions of years. At the bottom of the scale, red represents very young oceanic crust, formed less than 9.7 million years ago. The oldest oceanic crust is represented in blue, and is between 154 and 280 million years old. Data are only shown for areas of the plates that consist of oceanic crust and for which the age is well determined. No data are shown for the land areas because they are underlain by continental crust. No data are shown for some continental margin areas because the sediment cover is great and it is not Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson

Asynchronous Plate Tectonics Lab developed for Teach the Earth currently possible to determine the age of oceanic crust there. No data are shown in some high latitude areas because there are not yet sufficient data collected there to reliably determine ages. Note that all oceanic crust on Earth is younger than about 280 million years. This is actually surprising given that the Earth was formed about 4,600 million years ago and there are areas of the continents where the rocks are known to be almost 4,000 million years old. The oceans are young because old ocean crust becomes quite dense and tends to be subducted back into the mantle. Thus, ocean crust does not typically hang around on the surface of the Earth for a long time (geologically speaking, that is). Continental crust is less dense than ocean crust, both when it is young and when it is old, so it tends to stay at the surface nearly forever. These ocean crust age data are from the U.S. Geological Survey. Map C: Volcanology Each triangle on this map represents some type of volcanic activity active within the last 10,000 years. Three types of volcanoes are shown using three different colors, and hollow triangles indicate submarine volcanoes. The data are from the Smithsonian Institution, Global Volcanism Program. Map D: Heat Flow This map shows the predicted distribution of heat flowing from Earth’s interior to Earth’s surface. This map is based on surface measurements combined with fourteen other observable features ( Lucazeau, 2019). Heat is a form of energy, and here it is being measured in milliWatts per square meter. Watts is the standard measure of energy (just like for lightbulbs). Milli- means 10 -6 . The hottest areas (highest heat flow) are given in red, with a spectrum to deep blue representing the coolest areas (lowest heat flow). Map E: Topography and Bathymetry The colors represent the elevation of the land surface and of the bottom of the ocean. Elevation is expressed in the color bar in meters. The pale yellow through green and blue and then purple colors are shallow to deep ocean areas. The dark gold through brown, are low to high land elevations. These data were obtained from the “ETOPO1 Global Relief model” dataset from the U.S. Geological Survey. ETOPO1 stands for Earth Topography at 1-minute spacing. Map F: Plate Boundaries This is a somewhat generalized plate boundary map to be used as a base map for this exercise that you will submit to your instructor. While most plate boundary locations are generally agreed upon by scientists, some are not. Other plate boundary maps may be expected to deviate from this one in certain details. Neither is necessarily right or wrong. To get at the differences, one must dig deeper into the observations and interpretations than is appropriate for this type of classroom exercise. Therefore, do not be surprised if your map deviates from others and those you might find using other resources. These data were obtained from the U.S. Geological Survey. Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson

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