NASA Educational Workshop
SeaWiFS: Land Processes
Eastern Canada - Summer
This image was taken on June 4, 1999. It shows the southern portions of
the province of Quebec in eastern Canada. North is at the top of the image.
The large river running across the lower right corner is the St. Lawrence
River. To the south of the river is the province of New Brunswick.
- The different shades of green indicate different types and amounts of vegetation. Blue-black areas indicate rivers, lakes, seas.
Take a look at the patterns that the vegetation, rivers, and lakes make in this image. From this information, what can you say about the topography of the land? Is this region flat? Or is this region very rugged, with many hills and valleys?
- This area has been run over by glaciers in the recent geological past. Can you tell which direction the glaciers moved? Hint, there are two different directions of glacier motion that affected different areas of the image.
- Take a look at the circular lake at the top center of the image. It is approximately 70 km in diameter. How do you think this feature formed? What could have formed such a circular feature? On the Earth, circular features are formed by volcanoes and by meteors striking the Earth. Which process do you think was responsible here? Why?
This circular lake represents the remnants of an ancient impact crater (the Manicouagan impact feature). It was formed over 200 million years ago, during the Triassic Period, when a large meteor, travelling several times the speed of sound, struck the Earth forming a large bowl-shaped crater. Is the remnant we see still bowl-shaped? What do you think has happened over 200 million years to modify this crater?
The impact that contributed to the death of the dinosaurs, occurred around 65 million years ago, at the end of the Cretaceous Period, and formed a crater that is about 200 km across. The crater in this image is estimated to have been approximately 100 km in diameter, before it was erroded. Could the crater in this image have contributed to the death of the dinosaurs? How much destruction do you think the crater in this image would have caused?
- The grey areas in the bottom parts of this image represent cities; Montreal at the bottom, and Quebec City further up the St. Lawrence. Cities appear grey in this image because they have relatively little vegetation and show mostly concrete, pavement, and roof tops to the satellite. More greyish areas can be seen in the upper left corner of the image. Do you think these represent cities? Why do you think these areas have a similar grey look?
Eastern Canada - Winter
This image was taken on February 8, 2000. It shows more or less the same region as the image above, but in the winter.
- Compare this image with the one above. What are all the white areas in this image? Which areas tend to most white? Why?
- In the summer image city areas appeared grey. In this image, most of the land appears grey. Why? What has happened to the vegetation? What is the satellite seeing in the summer that it doesn't see in the winter and vice versa?
This series of images shows vegetation on the Australian continent for four different months, representing the four seasons. Green colors represent abundant vegetation, yellows represent little vegetation, orange and brown colors indicates no vegetation.
- Consider the vegetation images of Australia. Where in Australia is the vegetation found? Where in Australia is vegetation never found? What does the vegetation tell you about the climate of Australia as a whole?
- Compare the four images. Over all, when does Australia have the most vegetation? Which season is this? Remeber, in the southern hemisphere, the seasons are opposite to the northern hemisphere. When does Australia have the least vegetation? Which season is this? Is this similar to what you are used to at home? What does this vegetation pattern tell you about the climate?
- Compare the north part of the continent with the south part. When do the northern parts have the most vegetation? When do the southern parts have the most vegetation? Why do you think they are different?
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