Using historical photos to determine past environmental conditions
Intended Level: High School
Subject: Geology/Earth Science
Focus: Students will use a variety of sources including historic photographs to research the extent of "tree line" alteration in response to climate change in Rocky Mountain National Park (or another location). Students will examine "then and now" photos, determine if trees are growing at a different elevation between the two photos, and calculate the difference in average ambient temperature between the two time periods.
Standards Assessed:
Science Standard 1 Students will select and use appropriate technologies to gather and process data and to report information relating to an investigation.
Assessment:
The assessment will be in the form of a "formal" lab report. The students will:
a. Write the procedure used in their investigation.
b. Show examples of then and now photos as materials used.
c. Show critical thinking in the processing of the data to substantiate their claims in the conclusion.
d. Use concrete examples in their conclusions.
e. The students will follow the lab report rubric introduced in the week.
Time: One week of instruction.
Materials/Teacher Preparation:
- Access to computers with internet connection
- URLs to appropriate photos
- topographical map of locations
Possible Procedures:
This lesson can be adapted to any location by using historic photographs from sites such as the American Environmental Photographs collection, 1891-1936 University of Chicago Library and current photographs taken by the instructor.
Before beginning this lesson, students should have a background in geology and be able to read a topographic map. If students do not have this background, more time will be needed to teach these concepts
A. Have students access the "Then and Now" photos of Mystic Falls in San Miguel County, from the Aspen Historical Society Web Exhibit: "William Henry Jackson and John Fielder Photographs: Then and Now".
Mystic Falls c. 1893 < http://www.heritageaspen.org/images3/mysfllr.jpg >
Mystic Falls / San Miguel County, 1998 < http://www.heritageaspen.org/images3/mysf2lr.jpg >
With a topographical map of the location, help students to measure the degree of erosion over the past 100 years.
B. Using another "then and now" set from the "William Henry Jackson and John Fielder Photographs: Then and Now" Exhibit, such as Chicago Lake/Mount Evans Wilderness, or Durango Silverton Narrow Gauge RR, and a topographical map of the location, help students determine both an historic and present day tree line. Students will then calculate the difference, if any, of tree line in each of the photo pairs and display their results on the topographic map.
D. Now using the historical photos of Rocky Mountain National Park from the American Environmental Photographs collection, 1891-1936 University of Chicago Library :
[A] lake [at] Boulder[-Grand] Pass, Colorado
[A] wind-swept Engelmanns Spruce, Boulder[-Grand] Pass, Colorado
and current photographs taken in this location, have students calculate the difference in tree line in Rocky Mountain National Park.
E. Remind students that adiabatic cooling is the idea that the air temperature will cool as you climb in elevation. The adiabatic (dry) rate is about 3-4 degrees F/1000 feet. Help them through the following example: if we can deduce a rise of 1000 feet in tree line we can imagine that the air temperature has changed 3-4 degrees between pictures (or some ratio).
F. Students will then use the difference in tree line elevation calculation and the adiabatic rate to calculate the change in average ambient temperature.
G. Students will finish the lesson by writing up their lab report.
-Ed Adams, Colorado Online Learning
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