Electronic Lithographs

2002 Lithos

• EarthKAM Guide (pdf)
• EarthKAM Photography (pdf)
• Andalusia, Spain (pdf) -
  • Why are there fewer crops on this side of the river?
    The area on this side of the river is part of Donana National Park. It is bordered on the east by the Guadalquivir River and on the west by a much smaller river, the Rio Brazo de la Torre. The region is part of one the largest and best-known wetlands in Europe. Almost half the reserve area comprises swamps on flat clay soil filled with muddy sediments. Fewer crops exist on this side of the river because of the poor agricultural conditions and also because the area is strictly protected.
  • Why is the river water brown?
    The river water is brown because it contains high levels of sediment from the surrounding area. This can be caused by heavy erosion of the riverbed, riverbanks, and channel. It could also be the result of substantial rainfall, which can wash topsoil and other types of material into the river.
  • Why are these fields different sizes?
    The fields are different sizes because they are different crops. The larger fields are most likely grape vineyards. Andalusia is world-famous for its production of Sherry, a type of wine produced from Listan and Pedro Ximenez grape varieties. The smaller fields are presumably strawberries, oranges, and almonds, which are the main crops grown in this region. Their conditions for ideal growth differ, and inevitably so do their acreage.
• Buenos Aires, Argentina (pdf) -
  • Why isn't there agriculture in this region?
    This region has not been agriculturally developed due to the change of terrain in addition to the increased elevation of the area. The region is not as flat as the land to the west and is not as conducive to farming.
  • Why is Buenos Aires located here?
    Buenos Aires is in its present location due to the area's easy access to the Rio de la Plata. The Rio de la Plata provides several major benefits, including excellent commerce opportunities and the availability of fertile land for agriculture. One of the first major ports in the South Atlantic, the city was recognized for its commerce opportunities as early as 1776, when Buenos Aires became the capital of the newly founded viceroyalty of the La Plata province. Additionally, the availability of nutrient rich land and an ample fresh water supply from the Rio de Parana contributed to the area's desirability for both agricultural and city growth.
  • Where do the river sediments (sand and mud) come from?
    River sediments in the Rio de la Plata come from both the Rio de Parana and the Salado River. Loose particles upstream in the rivers, in addition to sediment that comes off of the riverbanks due to erosion, eventually make their way downstream to Buenos Aires and the Rio de la Plata.
• Cloud Patterns (pdf) -
  • What do different types of clouds look like from space?
    Cumulus clouds rise high into the troposphere but are prevented from rising higher by the stratosphere. As a result, the top begins to spread out sideways forming an 'anvil head'. The edges appear feathery due to water vapor turning to ice at the high altitudes. Cirrus clouds appear from space as a simple line of cloud. When there are many cirrus clouds in a row, they are also known as 'roll clouds' as they are sculpted into tight rolls by air currents. Storm clouds appear as a spiral, or pinwheel, over the earth. Severe storms such as typhoons or hurricanes appear as very thick pinwheels with a small space in the center where the eye of the storm is.
  • Can you tell which way the wind is blowing?
    Based off of the orientation of the picture, the wind is blowing down and to the left. This is evident by looking at the direction in which the feathery tail of the clouds is stretched out. Although the bulk of the cloud will be blown along with the wind, part of it will get drawn out behind the moving cloud. Clouds are composed of a mixture of lighter and heavier water molecules. When pushed by the same wind, the heavier water molecules will not move as far as the lighter molecules, so the heavier molecules get left behind. As a result, the tail will point in the opposite direction as the wind.
  • What properties of land and water influence cloud formation?
    Clouds form when water molecules saturate an air mass. Places on land that have significant elevation force air to rise, and with it water molecules that cool as the air rises and forms a cloud. If enough heating of air occurs on the ground, air becomes warmer and lighter and rises like air in a hot air balloon. When the air cools down, the vapor cools, liquefies, and it becomes a cloud. Clouds also form over land when there is a mixing of warm and cool air. Over water, the different areas of warmer and cooler water that correspond to differing depths form clouds in the same way as on land, due to the difference in air temperature.
• Colorado River (pdf) -
  • Why do these lines follow each other?
    These two parallel lines are two layers of strata on the lower limb of a western sloping monocline. They are actually younger rocks that had previously existed on top of the monocline, but have since been eroded off to the base of the slope. Such layers of sediment tend to closely resemble each other because they are part of the same mountain and consequently have been exposed to the same formation conditions.
  • Why is this area dark colored?
    The black color seen in this area is due to the high concentration of coal, a major fossil fuel. Coal is black because it contains a lot of carbon. The more carbon it contains, the blacker it gets.
• Creative Agriculture in Response to Limited Water (pdf) -
  • Which regions look like they've been cultivated recently? Which look older?
    In the picture of Australia, there is a small circular area of agriculture south of the lakes. The lighter colored rectangles in that area look more recent since there is no dark foliage to cover the terrain. The darker rectangles look to be older since plants have grown there and obscure the normal orange-brown color of the soil.
  • What evidence do you see of arid conditions in these areas?
    'Arid' refers to soil that is dry for more than half of the year and whose topsoil is not moist for more than 90 consecutive days. The absence of abundant foliage in areas away from irrigation is one indication of arid conditions. Any plants would be small so as to lessen the amount of water loss. Also, the orange brown coloration of the soil and surrounding terrain that is apart from the areas of irrigation indicates very dry weather and aridity.
• Earth Features Seen From Space (pdf)
• Forest Fires in Sumatra (pdf)
• Ganges River Deltav (pdf) -
  • What are the effects of sediment on a delta?
    Sediments are held suspended in the river's flow as long as it is moving fast enough to keep the particles suspended. When the river enters the ocean, it slows down and the sediment is dropped out. The deposition of sediments causes the formation and growth of the delta, and explains why it can take such complicated forms. When a channel fills up with its own sediment, it overflows, and a new channel (or channels) form.
  • What might be the sources of the sediment in the Ganges Delta?
    Sources for sediment in a river are any materials in the riverbed upstream of a given point, or even the surrounding areas, when the river floods and overruns its banks. Since the Ganges is a major river, it can carry down sediment from a large area.
  • Why are these areas white?
    White areas fringing the coast are usually beaches. In nearly flat areas, salt flats can sometimes form as well.
  • Why is this are vulnerable to tropical cyclones?
    Cyclones, hurricanes, and typhoons - these are all the same kind of storm, but the different names indicate where they occur: \"hurricane\" in the Atlantic, \"typhoon\" in the Pacific, and \"cyclone\" in the Indian. Tropical storms form due the interactions of warm seas and cool air. The Indian Ocean provides the former, and, during the early autumn, the cooler temperatures on land provide the latter.
• Gazankulu Homeland, South Africa (pdf) -
  • What is being preserved in this park?
    Kruger National Park is a wildlife refuge, space for native animals to be safe from hunting. Mammals protected by the park include buffalo and zebras, elephants and rhinoceros, giraffes, hippopotamus, antelope and impala, and cheetahs, leopards, and lions. The park is also home to a variety of reptiles, amphibians, and birds; including crocodiles, stork, and eagles. Native plants also find a refuge there, as the South African Parks Authority has undertaken to remove all foreign plant life from the park.
  • What are the livelihoods of people in this area?
    This is a rural area, and the people here raise livestock. The bare patches where the herds graze are visible, and show (by their absence) where the reserve's boundaries lie.
  • Why are the edges so straight?
    In some parts of South Africa, fires known as controlled burns are set to reduce the load of fire fuel (dry grass, downed trees, undergrowth) in a given area. A common practice in wilderness firefighting is to create fire breaks--areas where vegetation has been bulldozed away, depriving a fire of fuel to spread through. In setting controlled burns, this is often done first to prevent the fire from escaping the designated burn area. Fire is a natural part of the ecosystem, but unchecked fires can sometimes cause damage to important or fragile areas, as when fires approach population centers or wildlife refuges. Especially after wet winters, the dry heat of South African summers leads to a high fire hazard; large fires can also lead to increased erosion and even flooding during the following rainy season, as the plants that acted as ground cover (holding down the topsoil) have been burned away.
• Nile River Delta (pdf) -
  • Why does the color of the water change here?
    The color change seen here along the shoreline is most likely due to the presence and concentration of phytoplankton, sediment, or dissolved organic chemicals. Phytoplankton are very small, single-celled, ocean-dwelling plants that contain a chemical known as chlorophyll. Chlorophyll is used by plants to convert sunlight into nutrients and is responsible for the greenish color, seen here along the shoreline.
  • What are the gray patches inside the Nile River Delta?
    The gray patches that appear inside the river delta are densely populated settlements. Notice that the settlements are spread across the area fairly even, showing the tendency of humans to organize spatially in regular patterns.
  • What factors influence the location of agriculture?
    Environmental settings, as well as social factors can influence the location of agriculture. Some of these contributing factors include water availability, soil composition, humidity, and socioeconomic demand for the product.
• Northeast Coast of Australia (pdf) -
  • Why are Mackay and the surrounding agriculture here?
    The city and its surrounding farms are located here because of the limitations of the Connors Range surrounding them. The Connors sandwich the developed region between the mountains and the ocean. The presence of the river was probably an important factor in the initial settlement of the area. Most of Australia's population lives within 20 miles of the ocean.
  • Why does the water appear to be different colors?
    The color of the water can indicate depth (eg, darker blues in deeper areas) or the presence of particles suspended in the water. Lighter, greener areas (especially those with swirls and eddy patterns) indicate the flow and mixing of the water masses. The suspended materials here may be either sediment and runoff from the area's rivers, or, in this case, possibly salt precipitated out by high concentration or temperature.
  • Why are the agricultural fields arranged as they are?
    The fields are arranged to take advantage of most of the flat, usable land. Note the way the surround, but do not cover, the outlying hills.
• Rio Sadado, Argentina (pdf) -
  • Why are these small rivers so bright? (Think about what the riverbed might be made of.)
    These free-flowing rivers have sediments carried along in their channels; in this case, the sediment carried from upstream is of a lighter color than the surrounding area. Also, this photo was taken in October, which is early spring in the southern hemisphere. Early snowmelt in the Andes may be swelling these small rivers, increasing their speed, and creating whitewater. Compare these small rivers to the larger, dammed river. Note that the reservoir is also light-colored. Since the dam causes water to back up behind it, the river flowing into the reservoir slows down, and deposits its sediments there. The river flowing out through the dam appears light-colored for a short ways, where its speed is probably great enough to create whitewater. Farther away from the dam, however, it has resumed a slower pace, and since it no longer carries any sediment, it appears dark.
  • Why are these areas uncultivated?
    The areas to the edge of the photo are not under cultivation because this area is hilly. In mountainous regions, hillsides are cultivated using terraces, but where flat arable land is still available, the benefits of additional fields do not overcome the difficulties of building terraces. However, the hilly terrain and the change in elevation make possible the creation of a reservoir behind a dam, as can be seen here.
  • Why are they different colors?
    The agricultural fields will have varying colors, depending on what crop is being grown in them. Each separate field, however, will show very little color variation within itself, since most plots will be planted entirely of the same crop.
  • What is the importance of water in this area?
    Water is critical to any agricultural area. Most food crops cannot grow well enough to be profitable without some sort of irrigation, and access to a natural water source (such as a river) can provide some insurance against years when rainfall may be inadequate. The shape and size of the fields near the river (\"long lot\" parcels) show how access to the river is made available to many separate fields.
  • How does the agriculture near the river differ from agriculture away from the river?
    Near the river, the fields are arranged in long, skinny plots radiating away from the water's edge (with the narrow end along the water). Away from the river, the plots become rectangular and regularly arranged. The riverside parcels are the older, individual farms, while the fields out in the plain are newer, and larger farms, probably irrigated by canals.
• San Jose, California (pdf) -
  • Why is the city located in the valley?
    San Jose was originally established in the heart of the Santa Clara Valley because of the area's rich soil and adequate water supply. Agriculture once flourished under these settings, but the area has since been nicknamed the Silicon Valley, after the decline of agricultural-based products and the rise of high-tech computer related industries.
  • Can you tell what time of day it is from the shadows on the mountains?
    The sun rises on the eastern horizon and sets on the western horizon. Because the surrounding mountains are shadowed on their eastern slopes, we can discern that the sun is shining from the west. This picture was probably taken in the afternoon, somewhere around 3pm.
• Tibetan Plateau (pdf) -
  • Why is there less snow around the lake?
    There is less snow around the lake because although the lake itself is at a high altitude, it is still at a significantly lower altitude than the surrounding snow-covered mountains. As a result, the temperature is warmer near the lake than up high on the mountains so there will be less snow. Additionally, the weather in the area is typically very dry and cold rather than wet and cold. This means there is very low moisture in the air which means that there is less water vapor to become cooled in the atmosphere and become snow.
  • Why is one side of the lake bluer than the other?
    Looking closely at the picture, it is possible to make out fine lines on the surface of the lake. These lines, which can be seen throughout the entire lake, indicate that the lake is frozen. The lines depict cracks in the ice. There is a difference in the coloration of the lake's surface because the thickness of the ice over the lake varies. The lighter areas of the lake show areas of thicker ice whereas the darker portions of the lake are thinner.

Lithos From Previous Printings

• Deforestation in Rondonia Brazil (pdf)
• Eruption of Klyuchevskaya Volcano (pdf)
• Mississippi River Delta (pdf)
• Space Cameras (pdf)