The Old Man of the Mountain was a rock formation on the side of Cannon Mountain in New Hampshire. Scientists believe it formed 200 million years ago when the mountain was covered in glaciers. New Hampshire is known for its harsh, snowy winters. In the 1920s, scientists started noticing large cracks in the face of the mountain. In 2003, the rock formation collapsed. The picture on the left shows the rock structure before its collapse. The picture on the right shows how the rock structure looks today. (The ghost image shows the part lost in the collapse.)

Part A

Explain the geological processes involved in creating the Old Man of the Mountain rock formation.

Part B

What factors likely caused its collapse?

Part C

Explain how both gradual and fast changes to Earth’s surface contributed to the collapse of the Old Man of the Mountain.

Question 2

Niagara Falls is eroding. But the average rate at which it is eroding has changed over time because of human activity. This graph shows the total erosion of Niagara Falls starting in 1900. (The falls were eroding before 1900, but we’ll look only at the changes after 1900 for this study.)

Part A

Based on the graph, determine how many total meters the falls eroded from 1900 until 1910.

Part B

How many meters of the rock wall eroded between 1910 and 1927?

Part C

The graph is steeper between 1900 and 1905 than between 1905 and 1927. What does the steepness of the line represent?

Part D

Let x be the number of years that have passed since 1900 (at 1900, x = 0). Let y be the total meters of erosion. Write an equation in terms of x and y to represent the erosion at any point between 1900 and 1905.

Part E
What caused the rate of erosion to change around 1905 and 1906?

(Hint: to find the rate of change between the points, take the change in y and divide it by the change in x.)

Part F

Hydroelectric dams convert kinetic energy from moving water to electrical energy. Why do you think the rate of erosion decreased after the power plant was built?