Geology 1203 Earth history Assignment - Nova Scotia Geology Map The rocks of Atlantic Canada represent almost a billion years of history and record the tectonic events that have shaped this planet and this region. From mountain building collisions of continents to rifting that split apart the supercontinent Pangea, it is all recorded in the rocks. In this assignment we will take a look at the ages and types of some of the rocks that form Nova Scotia. We will be working with the Geology Map of Nova Scotia. This publication contains an amazing amount of information and is recommended for anybody interested in the rocks and geological history of this province. But before we can start we have to understand how to read a geological map. How Rocks are Named To identify layers of rock, geologists have created several categories to distinguish one rock layer from another. The basic unit in this system of classification is the formation. Often this will be abbreviated to Fm. in usage. The Halifax Formation, or Halifax Fm. for example. A formation is a rock unit that has a distinctive appearance; a geologist can tell it apart from the rock layers around it. Formations will usually have one distinctive type of rock, the Halifax Formation is predominately slate, but they may often include a variety of rock types. Formations must also be thick enough and extensive enough to plot on a map. Formations can also be subdivided into smaller units called members (Mb). Formations can also be lumped together into larger units called groups (Gp). The Meguma Group is comprised of the Halifax and Goldenville Formations. Members make up formations. Formations make up groups. When geologists propose a new name, they must publish a formal description that includes a full description of the rock unit and the location of the type locality. The procedures for classifying and naming rock units are contained in the North American Stratigraphic Code, prepared by the North American Commission on Stratigraphic Nomenclature. All unit names are formal and should be capitalized in use. Map Reading Geological maps are overflowing with information but you have to know how to extract it. The rock units (members, formations, and groups) are indicated with different colours and symbols. The age of the unit is often conveyed by the stylized letter that represents a specific period in the geologic time scale. A unit that spans more than one period in age will have both letters. This symbol indicates that this unit is of Devonian - Carboniferous age (DC). The smaller letters following refer to the unit name (or in some cases the rock type) - in this case the Fountain Lake Group. Sometimes a smaller letter will precede the age indicating the epic; for example, E-early, M-middle, L-late. All this information is recorded in the map legend. Next to the symbol there will be a description of the unit that it represents. What do I do? Look in the Media Library for the Maps folder. You should see the link for the Nova Scotia Geology Map (side A). This will take a few minutes to load depending upon the speed of your computer and internet feed. This uses a program called Zoomify to allow you to view the map and using the controls you can pan, zoom in and zoom out. Table of Formations First we will look at the legend for the map, located in the bottom right corner. Here it is called the Table of Formations. Note: You will have to refer to the legend often so you may want to either print it, or open it in another window. I have provided it as a separate file in the weekly folder for you. You will notice that it is divided into a number of columns that represent different regions of the province that have different geological histories. Later in the course you will realize the significance of this. For now you need just know that the ages and types of the rock units vary as you move across the province. The left-hand side of the legend is the geological time scale. By tracing a specific unit horizontally across the table we can see the age of the rocks in millions of years before the present (Ma) and the time period. For more information refer to the section of the map titled “How to Use the Map”. Geology Map of Nova Scotia The map itself shows the distribution of bedrock units. This does not mean that these rocks are exposed everywhere. Much of the province is covered by Quaternary age glacial sediments and so the amount of outcrop will vary. There is a wealth of information on this map so take some time to read the various sections of text as you search for the answers. What do I submit? Answer the following questions. Be sure to use the proper number and letter for each. Question 1. Locate the city of Halifax on your map. There is a large mass of rock represented by pink and white that lies to the west of the city and extends almost to the western tip of the province. a) What type of rock is this? b) What is its age in millions of years (Ma)? c) What period does this correspond to? Question 2. Underlying peninsular Halifax and extending across the harbour to Dartmouth are the rocks of the Meguma Gp. a) What formations comprise this group? b) What type of rocks does each formation represent? c) What are their ages (periods)? d) Which of them do you think is younger? Question 3. On the Northwest coast of the province lies a narrow band of rocks (yellowish-green colour) that border the Bay of Fundy. a) What is the name of this unit? b) What is its age? c) What type of rocks are they? Question 4. Look at the four regions in the Table of Formations. Ignore the column of intrusive rocks for now. a) What is the age (period) of the oldest rocks you can find (not under the intrusive column)? b) In what part of the province are they located? c) What is the age (period) of the youngest? d) In what part of the province are they located? Question 5. Find the following symbols on your map. For each indicate the unit name, age, and the type of rocks represented. a) b) Question 6. Find the unit represented by the following symbol in the Table of Formations. a) b) c) d) What is the name of the unit? What is the age (period)? What type of rocks does it represent? What part of the Province (as divided in the Table of Formations) does it occur? (you will have to look carefully as this is only exposed as a long narrow band). Question 7. Locate Chignecto Bay, an arm of the Bay of Fundy, near the border with New Brunswick. This coast is the site of Joggins fossil cliffs; now a World Heritage Site. a) What is the name of the unit that underlies Joggins? b) What type of rocks are these? c) What age are they? Use the assignment link to upload your answers. References; Nova Scotia Geology Map 1994 Atlantic Geoscience Society
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