# Geology 101

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```					Geology 101 (20 points)                                     Name

Landslide along S.E. 224 Street near the Soos Creek Trail

Goal:1) to observe and describe the features of this mass movement, 2) to identify the type of mass
movement that has taken place, 3) theorize about the potential for future mass movement.

History:
The landslide is along the western valley wall above the popular Soos Creek Trail. The first
observed movement in this landslide occurred in January, 1998. The landslide moved 3-5 feet in this
initial phase. The movement was reactivated in December, 1998. The movement was up to 15 feet
horizontally during this most recent movement.

The landslide was of significance not only to the landowners on the hillside, but also to the
Bonneville Power Administration who had a major power pole in the path of the landslide. The pole was
re-located in early 1999.

Note: We must respect the private property of the individuals along this road. Do not leave the
224th St. access. If you need help or have questions, please see me.

Date & Time of Observations:

Observing Conditions:

Stop 1. Soos Creek Bridge. Mark the location of stop #1 on the “Google Earth” satellite photograph at
the back of you lab and answer the questions below.

 Describe how the size and profile of Soos Creek differ at this location (here near the
headwaters) compared to the location of our first field trip; estimate the depth and width of
the stream?

 Estimate the velocity of the water in this location. How does it compare with the velocity
we saw on the previous field trip?

1
Stop 2. Valley Floor = base of the mass movement: Mark the location of stop #2 on the “Google Earth”
satellite photograph at the back of you lab and answer the questions below.

 Draw a sketch of the valley in side-view including an estimate for scale. Indicate what direction
you are facing (north or south) on your sketch.

 What is the primary force that formed this valley- stream erosion or glacial erosion. Justify your

 What are three specific characteristics of this area that tell you that a landslide has occurred here?

1.

2.

3.

 What type of mass movement is it? What is the best evidence that indicates this to you?

2
Stop 3 = In the center of the slope that has moved.: Mark the location of stop #3 on the “Google Earth”
satellite photograph at the back of you lab and answer the questions below.

 What are two specific characteristics of this area that tell you that a landslide has occurred here?

1.

2.

 What type of movement occurred here? Justify your answer (= describe how the movement here is
similar to/ different from the movement at the base of the slope).

 What are the four primary ways that we can mitigate mass movement?
1.

2.

3.

4.

 Which of these approaches have been used here? List two ways the recent construction is trying to
stabilize the slope:

1.

2.

3
Indicate on the picture below the position of each stop.

4

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