Illustrations for a lecture called

Changing the world: Documentation of large-scale human-induced earth-surface change in images from satellites, the Space Shuttle program, and the International Space Station

     This is the first of two pages presenting the illustrations for a lecture (or more reasonably two lectures) on large-scale land use given by Dr. Bruce Railsback in his GEOL 1122 course Earth's History of Global Change at the University of Georgia. The links below are to large (generally 900-pixel-wide) jpeg files. The large size of those files is to allow educators to use the images in classes and presentations. For further information, contact the author at
      Railsback would be happy to give this talk to interested groups. In an hour he can either talk about the US examples and in doing so talk about forests and deforestation, grasslands, and wetlands, or in an hour he can talk about world-wide examples of deforestation. In two hours, he can bore you to tears with the entire show. If you're interested, contact him at

Shortcut to the second page





Title slide
General Conclusion

      The left-hand image on the title slide shows the kind of imagery on which this talk will focus. It's a satellite image showing the spectacular green bull's-eye of Mt. Egmont National Park in New Zealand. This circular park stands out so clearly because it has its natural forest cover, whereas as the land around it is bucolic but very unatural farmland and pasture-land. These kinds of contrasts illustrate the difference between lands in their natural condition and lands changed by human use. The former are almost always the tiny minority, and the latter the vast majority, of the landscapes we'll see.
     To make it clear where we're going, the second slide gives the very general conclusion of the presentation. There will be more specific conclusions toward the end.



The southeastern U.S.



Northeast Georgia
The Savannah River Site

A peanut field in the Coastal Plain
Soybean and cotton fields in the Coastal Plain
A field and tree farm in the Coastal Plain
A tree farm in the Coastal Plain

Pasture in Oglethorpe County
More pasture in Oglethorpe County
Woods at Watson Mill Bridge State Park

Atlanta infrared images
Temperatures in NW Atlanta

A little of Lake Hartwell
A clear-cut area, from the air
A clear-cut area, from the air, in more detail
A clear-cut area, from the ground

      We can start close to home with a look at northeast Georgia. One of the most striking features is a round dot of green southeast of Augusta - it's the Savannah River Site, and it stands out because it is tree-covered in the largely deforested (and thus much lighter-colored) coastal plain. Where there are stands of trees in the coastal plain, they are commonly tree farms that are monocultures of pine.
      In the Piedmont, north of the coastal plain, there are fewer farm fields but a fair bit of pasture land. As the "Oglethorpe pasture" images show, the result is a green countryside of meadows pleasing to the eye. Those meadows are, however, completely unnatural: the "Watson Mill Woods" image is from a state park where vegetation much more closely approximates the natural condition.
      To the west in our image of northeast Georgia is Atlanta, an area where land use has obviously changed the land surface. Less evident is the resulting change in climate. Studies have shown that Atlanta is a striking urban heat island, and the images here show that Atlanta glows in the dark (at least in the infrared band) and that temperatures are extremely elevated in thoroughly paved areas. As a result, Atlanta has to an extent its own weather, with thunderstorms triggered by the heating over the city.
      To the northeast in our original image is Lake Hartwell, where aerial photographs show just a little of the extent of this human-made lake. Detailed images show logging roads and the results of clear-cutting.

      The punch lines here are that unexpected preserves like the Savannah River Site, a nuclear lab, can be our best indicator of what land cover should look like; that bucolic pastures are nice but unnatural; and that cities represent more environmental change than we realize. From the first two come the generalization that deforestation is more common than we usually recognize. Forest cover like that at the Savannah River Site covered North America from the Atlantic shoreline to the prairies of the Great Plains, but now the Savannah River Site is a small green dot on the deforested landscape.



The northeastern U.S.



Southeastern Pennsylvania and northern Maryland
Western Pennsylvania and eastern Ohio

Jefferson Proving Ground and Indiana, Ohio, and Kentucky
Farmland in Wayne County, Indiana
A small wood amidst farmland in Wayne County, Indiana

Eastern US Forest cover - then and now

      Northerners tend to tell southerners that everything is done better up north, and that seems to be true of the present state of deforestation. The first image, from southeastern Pennsylvania and northern Maryland, provides a strong contrast between the light-green-and-white deforested regions and the dark green of the Allegheny ridgetops. The area of the former is much greater than that of the latter. The same is true of the second image, where the dark green Allegheny ridgetops give way to the deforested farmland of western Pennsylvanian and eastern Ohio. In the northwest part of the image, the grid of roads at one-mile intervals becomes apparent as an indicator of how thoroughly a human-dictated imprint has been imposed on the once-natural landscape.
      In southern Indiana, one can see the contrast between natural land cover and deforested areas by examining the Jefferson Proving Ground. Despite decades of weapons testing, the proving ground stands out as a rectangle of forest amidst hundreds of miles of largely deforested and farmed countryside. A closer look at that farmland comes from Wayne County, Indiana, and a small woods there (on-the-ground pictures to come). More obvious is the change in the landscape caused by development of Indianapolis.
      Again, the punch line is that North America was covered by forest from the Atlantic shoreline to the prairies of the Great Plains, but now isolated remnants are all that survive to contrast with the deforested landscape. We see small woods and isolated trees as we drive across this landscape, but the overwhelming majority has been deforested.



The Upper Midwest



The Upper Midwest
Northeast Iowa

Forest in southeastern Iowa
Forest in southeastern Iowa
Forest in southeastern Iowa
Forest in southeastern Iowa
Farmland in southeastern Iowa
Farmland in southeastern Iowa
Farmland in southeastern Iowa
Farmland in southeastern Iowa
Farmland in southeastern Iowa

Putnam Park, Eau Claire, Wisconsin
Putnam Park, Eau Claire, Wisconsin
Putnam Park, Eau Claire, Wisconsin
Farmland near Eau Claire, Wisconsin
Farmland near Eau Claire, Wisconsin
Farmland near Eau Claire, Wisconsin
Farmland near Eau Claire, Wisconsin
The Great Peshtigo Fire of 1871

Hayden Prairie preserve, northern Iowa
Hayden Prairie preserve, northern Iowa
Hayden Prairie preserve, northern Iowa - a May wildflower sampler
Hayden Prairie preserve, northern Iowa
Farmland near Hayden Prairie Preserve, northern Iowa
Farmland near Hayden Prairie Preserve, northern Iowa
Farmland near Hayden Prairie Preserve, northern Iowa

      The first image here continues the theme we've seen earlier - vast expanses of light green deforested land, with a few dark green anomlies of natural forest cover. The yellow arrows point to some of those anomalies, which are labeled at the left. This image covers so much territory that the grid of roads is barely visible, but the image of northeast Iowa shows the striking rectilinear grid that makes the Midwest look like a very unnatural carpet.
      Two sets of images from the ground illustrate the contrast between the tiny remnants of forest and the surrounding vast areas of deforested farmland. The first, from southeastern Iowa, shows the extent and arboreal diversity in the Shimek State Forest and the deforestation of farmlands nearby. The second set shows Putnam Park, a tiny forest preserved from the wave of lumbering across Wisconsin in the late 1800s, and the far more extensive deforested farmland of western Wisconsin. That's the main point of this website; the much greater extent of very altered land relative to the sparse remnants of natural land. A final slide documents one other effect of lumbering in Wisconsin, the massive fire that swept the state in 1871.
      Farther west, prairie rather than forest has been swept away to make farmland. One remaining sample of that prairie is the Hayden Prairie preserve in northern Iowa. Around it for tens to hundreds of miles are farmland from which prairie grasses and flowers have been eliminated. Note the sign proclaiming Hayden Prairie as one of Iowa's largest prairie preserves - it's three eighths of a square mile amidst hundreds of square miles of farmland.



Agriculture on western grasslands



A quilt of circles?
Irrigation near Garden City, Kansas
Center-pivot irrigation

Some dustbowl images
A Texas dust storm in 2003

      The first slide in this set looks like a colorful quilt of circular patches, but it's acutally an image of former grasslands in western Kansas. Center-pivot-irrigation (irrigation with pipe sweeping a circle around a central source) covers huge areas of former grassland here, as the second image shows. Almost none of the origianl grassland ecosystem is preserved.
      Extensive disruption of these grasslands and exposure of their soil to wind provides a tremendous opportunity for erosion by wind. One result was the famous "Dustbowl" era of the 1930s, when wind-blown dust buried buildings, equipment, and farms.



Deforestation near two mountain national parks



Rocky Mountain National Park
Rocky Mountain National Park image with labels

Yellowstone National Park boundary
Patterns of clear-cutting west of Yellowstone National Park

      Large parks, as well as weapons testing facilities, can preserve natural vegetation cover sufficiently to provide a contrast with the larger landscape. The first of these images is a three-dimensional image of Rocky Mountain National Park. At the right is a noticeably less green area. The second image, which is labeled with the park boundary, shows that the light green is the unprotected, and thus much more deforested, area outside the park.
      The same sort of contrast can be seen on the image from the west side of Yellowstone Natonal Park. Clear-cut areas create a patchwork in the Targhee National Forest west of the park, whereas the park has relatively continuous forest cover. If you've driven west of Yellowstone and seen lots of trees, bear in mind that it's standard practice to not cut the timber along the highways (as shown in the 'Patterns of clear-cutting" image) and thus leave seemingly undisturbed forest for the unsuspecting tourtists to see.
      The point of these images is not that all land should be national parks and no land should be deforested. The point is that parks are only a tiny minority of all land, and that the deforestation made evident in these images characterizes a much greater proportion of the land.



The state of the state of Washington



(Much of) the state of Washington
Central Washington
Central Washington - with labels

The Olympic Peninsula
A logging map of the Olympic Peninsula
Images from the Olympic Peninsula

      The first image of this set provides an overview of much of the state of Washington, and the second image focuses on the eastern part of the first, and thus on central Washington. Several unnatural patterns are apparent, including a green-and-white checkboard in the Cascades to the west, swellings and thinnings of the Columbia River, and a green-and-tan patterning of the east. The labeled image shows the origins of these patterns: grants of alternating square miles of land to the railroads, damming of the Columbia, and resultant irrigation east of the Columbia (and in part to the west of it too).
      The first image of the Olympic Peninsula, home of Olympic National Park, shows subtle variations in land cover. The second slide shows that origins of those patterns: logging in the state and national forests has removed much of the surronding forest cover, and continuous forest remains only in the park. A third slide shows some images from the ground.



Owens Lake, California



Unlabeled image of the Owens Lake region
Labeled image of the Owens Lake region
Owens Lake from the ground
Owens Lake from the ground
Dust from Owens Lake

LA at night

      This set of slides begins with a remarkable view of mountainous terraine, with a dark pink smudge in the middle. That pink smudge is the remains of Owens Lake in southeastern California. Owens Lake was a large saline lake covering hundreds of square miles in the 1800s and early 1900s, but its water was diverted to the Los Angeles Aqueduct beginning in 1913. As a result, Owens Lake dried up to a briny salt pond now made pink by halophilic bacteria. Winds carry dust off Owens Lake, creating dust storms that are a health hazard to the south and east.
      This impressive piece of environmental change, along with other diversions of California rivers, has allowed the development of Los Angeles into one of the world's largest and most exciting cities. Whether the destruction of lakes in eastern California is justifiable as the cost of buidling great thirsty cities on the coast is perhaps a matter of one's judgment and priorities. However, even persons favoring humans over lakes have to consider the health hazards to humans as dust comes off desiccated lands like Owens Lake.



The Colorado River and Imperial Valley



The Colorado River basin
Dams on the Colorado River
Imperial Valley and the Salton Sea
Scenes in Imperial Valley
The Colorado River Delta - an overview
The Colorado River Delta - details

      The first slide of this series shows the Colorado River basin in southern California, Nevada, Arizona, and southern Utah. The second image is labeled with dams on the Colorado River. Those dams divert so much water to agricultural and residential use that hardly any water reaches the Gulf of Mexico, as we'll see below.
      Some of the Colorado River's water is diverted to support agriculture in the Imperial Valley north of Mexicali and Calexico. Runoff from the fields supports the Salton Sea, a lake that did not exist in historical times until failure of an irrigation canal flooded it in 1905. Today the Imperial Valley is a thriving agricultural area, but there is talk of taking its water, diverted from the Colorado River, and diverting it even farther west to support the needs of San Diego and far southern California.
      The result of all these diversions is that the Colorado River is dry as it approaches it ancient delta in the northern Gulf of California. Salt water from the Gulf fills its channel in the upper reaches of the delta, and salt flats abound where fresh water would naturally flow. King Canute famously tried to stop the tide, and failed, but human consumption of water has stopped a major river here.



Hawaiian deforestation



A sharp boundary

      Our last stop in the U.S. is in Hawaii. Here, the change in the landscape is due to overgrazing on one of the Big Island's huge cattle ranches. The result is a sharp contrast between relatively natural vegetative cover and degraded forest. The latter is considerably more common than the former.






An image of western Europe
The extent of Western European forests in the Middle Ages
France, southern Germany, Switzerland, western Austria, and northern Italy
The Black Forest and the Bavarian-Tirolean border
Bavarian farmland
Bavarian farmland
Tirolean farmland: valley floor
Tirolean farmland (valley floor) and lumber
Tirolean farmland on slopes

Northeastern Germany
Northeastern Germany - a labeled image

The Po Plain

The Netherlands - an unlabeled image
The Netherlands - a labeled image
Berkmeer Polder

      If it seems that we're picking on the U.S., we'll now go elsewhere to look at deforestation and other change of the landscape. Western Europe provides a good example, in that historical documents provide evidence of widespread forest in the early Middle Ages. Today the landscape is extensively deforested. Images from the Black Forest and the Bavarian-Tirolean border region in the northern Alps provide exceptional examples of forest against which comparison shows that deforestation is the rule. The same is true in northeastern Germany, where the forests of the Harz Mountains provide the only remaining example of dense forest cover. To the south, an aerial photograph from the Po Plain shows the extent of landscape modification: hardly anything natural is visible for miles.
      The image of the Netherlands shows interesting and obviously unnatural huge polygons. Those are the polders of land made from wetlands on the Dutch coast. Succcessive huge projects have generated vast tracts of new land for farms and towns where wetlands once filled the landscape. This remarkable reorganization of the landscape allowed the Netherlands to add a twelfth province without expanding its borders in 1986, when Flevoland was added to the previous eleven.



The Aral Sea



The Aral Sea in 2003
The Aral Sea through time
The Aral Sea from the ground

      The Aral Sea was once the world's third or fourth largest lake, but it's not anymore. Deviation of the lake's rivers for agriculture has caused the lake to shrink and dry up, leaving behind salt pans littered with the rusting remnants of fishing boats and barges that once busily crossed the lake. Commercial fishing on the lake ended in 1982, and today the waters of the Amu Darya and Syr Darya rivers go mostly to irrigate cotton fields and rice paddies in Uzbekistan, Turkmenistan and Tajikistan. Thus the stories we encountered at Owens Lake and in the Colorado River delta are hardly unique, and the Aral Sea is almost certainly headed toward the same fate.
      One might argue that the human gain from irrigation of agricultural lands justifies the destruction of the lake. However, human loss around the lake is intense: the economy of the lake region has been devastated, water supplies are fouled or non-existent, infant mortality is soaring, and kindey and thyroid diseases flourish. Environmental change has thus allowed econimic progress in some areas, but only at the expense of human devastation in another.
     (source: "Requiem for a dying sea" -






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