Essential Lens: Analyzing Photographs Across the Curriculum
Processes of Science: Mars, a Case Study #6018 Remnants of Ancient Streambed on Mars
Date: September 14, 2012
Photographer: NASA’s Curiosity rover
NASA’s Curiosity rover found evidence for an ancient, flowing stream on Mars at a few sites, including the rock outcrop pictured here, which the science team has named “Hottah” after Hottah Lake in Canada’s Northwest Territories. It may look like a broken sidewalk, but this geological feature on Mars is actually exposed bedrock made up of smaller fragments cemented together, or what geologists call a sedimentary conglomerate. Scientists theorize that the bedrock was disrupted in the past, giving it the titled angle, most likely via impacts from meteorites.
The key evidence for the ancient stream comes from the size and rounded shape of the gravel in and around the bedrock. Hottah has pieces of gravel embedded in it, called clasts, up to a couple inches (few centimeters) in size and located within a matrix of sand-sized material. Some of the clasts are round in shape, leading the science team to conclude they were transported by a vigorous flow of water; the grains are too large to have been moved by wind. Broken surfaces of the outcrop have rounded, gravel clasts, such as the one circled in white, which is about 1.2 inches (3 centimeters) across. Erosion of the outcrop results in gravel clasts that protrude from the outcrop and ultimately fall onto the ground, creating the gravel pile at left.
Scientists enhanced the color in this version to show the Martian scene as it would appear under the lighting conditions we have on Earth, which helps in analyzing the terrain.
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Supplementary: Essential Lens: Processes of Science - Mars, a Case Study
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Program 1 A Closer Look (video)
This introduction to the course models the process of analyzing photographs with teachers and students. Photography historian Makeda Best discusses the Focus In method with teachers, and educator Julie Keefe employs the method with students at a photography exhibit on "light and dark." Photography curator at the Portland Art Museum, Julia Dolan discusses how she carefully selects a set of photographs to tell a larger story.
Program 2 Witness (video)
Photographs bear witness to world events and help us to learn more about people, places, and situations -- historical and present day. Middle school teacher Donald Rose guides students in analyzing photos from school integration movements of the 1960s. Documentary film producer Ken Burns weaves photographs into historical narratives to bring the past to life. Photojournalist Louie Palu's photos take us deep into mines and war zones, and engage us with the individuals who take on those tasks.
Program 3 Lives (video)
Lives explores the story of human resilience and perseverance. Middle school teacher Donald Rose uses the Migrant Mother photos by Depression-era photographer Dorothea Lange to help students understand what elements a photographer chooses to focus on to create the greatest impact. Historian Linda Gordon, biographer of FSA photographer Dorothea Lange reveals Lange's role in engaging Americans in the plight of those who were most devastated. New Orleans documentary photographers Keith Calhoun and Chandra McCormick talk about the transformation of their photographs after Hurricane Katrina and working with young photographers to preserve the city's cultural heritage.
video 4 Evidence (video)
An image can show us otherwise invisible processes, previously undiscovered life forms, and dramatic change over time. High school teacher Rima Givot engages her students with highly magnified photos of mouse muscle to study genetically modified organisms. Scientist and photomicrographer Dennis Kunkel demonstrates the fascinating process of creating photographs of the microscopic world. Environmental photographer Gary Braasch reports on his worldwide travels to document the state of the planet through repeat photography.
Program 5 Story (video)
Every photograph tells a story: of struggle, of beauty, of community and culture. Social studies teacher Kim Kanof uses photos from the Protests and Politics collection to teach about protests around in the world in 1968. National Geographic photo editor Pamela Chen details the collaborative process of creating photo-based feature stories with design director David Whitmore. Iowa photographer Danny Wilcox Frazier discusses his work documenting the residents and images of marginalized communities across the United States.