Lab 8: Geological History and Maps

Question 1

when looking at geological sequence of events what options can it be

Answer 1

deposition
folding **
weathering and erosion
______ faulting
intrusion
contact metamorphism around structure

Question 2

uncomformity

Answer 2

surfaces or breaks in the geological records cause by erosion or periods of non deposition. Represented by a squiggly line

Question 3

disconformity

Answer 3

sedimentary rocks - the layers above and below are horizontal

Question 4

angular unconformity

Answer 4

the layer below is tilted or at an angle and the upper layer is younger and still horizontal

Question 5

nonconformity

Answer 5

igneous on the bottom, sedimentary above - there will be globs of igneous within the sandstone layer (and ofc a squiggly line)

Question 6

the surface of the Earth is what kind of unonformity

Answer 6

disconformity

Question 7

How to find the coal seam if given the structure contours (the many parallel line)

Answer 7

1. circle all points where the structure contour intersects with a specific contour line elevation
2. Your coal seam will be a line that goes through all of these circles

3.

Question 8

How to draw the second line on a surface trace if the ‘coal seam’ is thicker

Answer 8

1. Use the right hand rule to figure out which way the dip angle is pointed
2. The bottom of the is on the side with the angle - also your existing line
3. You will have an angle and an opp = thickness. Solve for x. Convert it to ruler scale
4. This is the distance and direction that you must draw a second structure contour next to your existing.
5. Circle all points that the new line crosses the specific elevation of contour lines. It should be the same elevation as the structure contour closest to it
6. Draw a second line for the coal seam by going through the new points you created and keeping about the same distance from the original coal seam.

Question 9

Process to do a Map for Three Point Problem

Answer 9

1. Connect 2 of your known points (you know their elevation).
   Lets say A=13, B=9
2. Write the distance between B to A as segments of 1 (or bigger magnitude of 1).
   9, 10, 11, 12 ,13
3. Notice the elevation value of the last point. C = 10

9-10 is 1/4 of the range

4. Find 1/4 of the way from point B. Mark this point.
5. Draw a straight line from C to 1/4 of the way from B. (This is your strike line)
   (if there is a 4th point, most likely, that 4th point will be along this new line)
6. Calculate strike in a normal fashion

Any points along this line are at the same elevation.

7. Draw a line perpendicular to your strike line. Connect it the first line you drew. Now use this line to solve for dip.