Examine the map of the Four-River Ridge. Refer to the map legend. What kind of rocks are found in this map area (circle all that apply)?
How many units can you see?
Carefully study the relationship between the contour lines and the contact between the limestone and sandstone. What does this tell you about the orientation of these beds?
Examine the gabbro unit. What V pattern is formed by the four rivers that cut through this unit? What does this tell you about the orientation of this unit?
What is the strike and dip of the sedimentary units in this map area?
What is the strike and dip of the gabbro dyke?
Draw a geological cross-section between the points X and Y indicated on this map. Note: you will have to prepare a cross-section from scratch for this exercise, but you can use the format from the Murky Mists cross-section as a guide.
Describe the geological history of the map area, a bulleted list is OK to use here. Hint: start with the oldest event and describe events as they occurred up to the present day.
Figure 16.16: Derivative of “Four-River Ridge” (CC-BY 4.0; Karla Panchuk via OpenPress) by Chloe Branciforte