E235 Lab 02 - Geologic Maps

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University of Waterloo *

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Oct 30, 2023

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Earth 235: Lab 2 – Geologic Maps Full Name: ____Tasneem Baten________ Student ID: __20989768_________ Please write or type your answer in the spaces provided and then submit to the Learn Dropbox. Provide short, clear answers to the following questions. Note that it does not matter which map you start with for this exercise but it is essential that you answer all questions in the boxes below. If your answers are not legible then they cannot be graded. 1. KAGAWONG AREA (Manitoulin District) - bedrock geology map (Ordovician and Silurian). 1a. Describe the organization of the legend on this map sheet? <2 marks> Organized with geological symbols, colors used to represent different types of rocks formations, and unconformities. 1b. Why are units 1a through 5 not coloured? <1 mark> Because these formations are mapped on some of the adjoining sheets of the Manitoulin Island Area. 1c (i) The geologic contact between Lower and Upper members of the Georgian Bay Formation (units 9 and 10) follows quite closely the shape of the North Channel shoreline. What does this tell you about the attitude of that contact? <2 marks> This means the contact is almost horizontal or parallel to the Earth’s surface in that area. This means it would strike east-west and dip South.

1c (ii) The geologic contact between Mindemoya Formation and the Fossil Hill Formation follows quite closely the shape of the Lake Kagawong shoreline. What does this tell you about the attitude of that contact? <2 marks> It strikes at 220degrees and dips at South-west direction at an angle of 310degrees. 1c (iv) Which formations (name and number of two) best illustrates the rule of the V’s? And which dipping direction do they indicate? <1 mark> Green Bay and Georgian Bay Formation. It is dipping towards South. 1d. With the answers to the above questions in mind – estimate the thickness of the Upper Member, Lower Submember of the Georgian Bay Formation (unit 10). Explain how you did this. Where is the best place in the map area to attempt this estimate? <3 marks> Thickness of Upper member: 200m Thickness of the lower Submember: 200m - Measure the vertical extent at various locations along the cross-sections and calculate the difference in elevation between the top and bottom of the unit to obtain thickness measurements. - Best place in the map is the North-West area.

2. SCARBOROUGH AREA map (Ontario) - surficial (Pleistocene) geology map. 2a. Describe the organization of the legend on this map sheet. <1 mark> The legend is organized with different types of rock formations and lithological patterns. 2b. What stratigraphic units would you expect to encounter in a borehole drilled to the bedrock at the main intersection in West Hill (centre of map area)? <2 marks> Sand of Lake Iroquois. 2c. The map scale is 1:31,680 or 1 inch to ½ mile. How would these numbers change if you photocopied the map and reduced its size to 50%? Show clearly how you derived your answer. <2 marks> 50% of the map scale is- 1:15840 For every 1 inch of reduced map, it shows half the distance of the original map Therefore, 1/2mile is going to be 1/4mile So the new map scale is 1inch to 1/4mile or 1:15840

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3. MADOC AREA - bedrock geology map (Precambrian and Paleozoic). 3a. Where are the most flat-lying rocks in this map area? Explain how you know. <2 marks> Limestone in the southern area of the map. - It can be determined by looking at the dip angles or rock formations in different part of he map. - Flat-lying rocks are represented by minimal tilting or folding. 3b. What kind of contact separates unit 13 from unit 9 in the southern part of the map area? How do you know this is not an intrusive contact? <2 marks> It is separated by unconformity contact. It is not an intrusive contact since intrusive contact would indicate one unit intruded into the other as a molten rock, which is clearly not visible on the map area. Also, because limestone was formed after unit 13 intrusion cannot occur back in time. 3c. What kinds of structural information are provided on the map? <1 mark> Geological contacts, faults, fold, strike, dip, jointing and fractures.

4. CAÑON FIORD (District of Franklin) - bedrock geology map. 4a. This area shows evidence for at least two major episodes of deformation related to orogenesis (mountain building). One episode is between the Devonian and the Carboniferous. Explain how this first episode can be determined? When did the second episode of orogenesis occur? <3 marks> The first episode can be determined by looking at the faults and folding between the Devonian and the Carboniferous. We can also look at the thrust faults to understand the direction and the intensity of the tectonic forces between the episodes. The second episode of orogenesis occurred in the late Triassic period. 4b. What kind of unconformity separates the Tertiary rocks from the underlying Paleozoic rocks in the southern part of the map area? Explain your answer. <2 marks> Angular Unconformity. There is a noticeable tilt between the older rocks, in this case, the Paleozoic rocks and the younger rocks (i.e. Tertiary rocks). The older rocks shows more tilting or folding than the younger rocks. 4c. There have been indications of fossils present. What does the presence of these fossils tell us? <1 mark> The geological age of the rock.

5. GLACIER LAKE (District of Mackenzie) - bedrock geology map. 5a. How can you determine the youngest possible age of the deformation in these rocks? HINT: look at the southwestern most corner of the map sheet. What kind of contact does the “Kg” unit show with the surrounding rocks? <2 marks> Look for cross-cutting relationship such as igneous intrusions or faults that cut across the ‘Kg’ unit. We can also determine if the ‘kg’ unit is overlain by or intrudes into the surrounding rocks. By looking at the map, ‘kg’ intrudes into the surrounding rocks. - Nonconformity contact 5b. What is the vertical exaggeration of the structural cross-sections at the top of the map? Indicate clearly how you derived your answer. <2 marks> Horizontal scale: 1:250,000 Vertical scale: 1:240,000 VE= vs/hs VE= 250,000/240,000 Therefore, the vertical exaggeration is 1.04 Do you have a better appreciation for maps? Maps are both beautiful and informative!

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