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This series of Landsat satellite images illustrates the landscape changes that are occurring in and around St. Marys, Georgia. The Landsat satellite sensor can detect light in the visible and infrared light from the sun. When using infrared light, scientists will often display as red in the an image. This works nicely for vegetation since plants reflect back most of the infrared light incident upon it. Notice that the trees in the accompanying images are red. Another advantage is that the human eye can discriminate more variations in the color red.
1972
In this image forested land appears dark red; thin forests, cultivated land, and exposed land appear lighter. The lighter colored patches among the forests are areas that have been cut or thinned. Something that is very bright in an image typically represents a reflective soil, rock, or constructed surface. The thin white strip along Cumberland Island is a beach. The lightly colored area north of the project study site is a spoil bank used to dump dredge material from the Intracoastal Waterway. Beaches and spoil banks are rather dynamic land features; look for them to change in successive dates. The white strip running along the left side of this image is U.S. Interstate 95. This section was only recently completed in 1972. Notice the quarries or borrow pits where material was mined, which are the white areas along I 95's path. Other developed areas in the image include the City of St. Marys and Fernandina Beach (lower right).
1984
Forest has returned in many areas in this image (the light red in 1972 is now darker red in 1984). The federally protected forest and beaches of Cumberland Island have changed little. The I 95 corridor is not as bright as it was in 1972. The area that was exposed soil and rock has matured with grass along the shoulders and median. Notice that the quarries are now filled with water. In the area around St. Marys an airport landing strip has been added. Directly north, infrastructure at the Kings Bay Naval base is expanded. The bright areas are exposed areas such as fields, roads, and buildings, and the large area to the northeast is a recently used spoil bank. The west side of the project study site has a new neighborhood in construction.
1991
Some forest change can been seen in this image while Cumberland Island remains stable. New residential growth is occurring in the south central portion of the image. Growth continues around St. Marys and Kings Bay.
2000
Again, forest can been seen returning to areas that have been cut or thinned. Forest clearing is evident west of I 95. Little change can be detected at Cumberland Island. Commercial and residential development are increasing. This is indicated by the light areas along I 95, the road to St. Marys, around St. Marys, and at Fernandina Beach. An additional runway has been added to the airport at St. Marys.
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