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SRTM Africa IMAGES


Information on:
Hi-Res. Tiff | Colored Height
Hi-Res. Tiff | Anaglyph of Shaded Relief
Hi-Res. Tiff | Richat Structure, Mauritania, Perspective View, Landsat image over SRTM elevation
Hi-Res. Tiff | Richat Structure, Mauritania, Anaglyph, Landsat image over SRTM elevation
Hi-Res. Tiff | Cape Town, South Africa, Perspective View, Landsat image over SRTM elevation
Hi-Res. Tiff | Cape Town, South Africa, Anaglyph, Landsat image over SRTM elevation
Hi-Res. Tiff | Olduvai, Gorge, Shaded Relief and Colored Height
Hi-Res. Tiff | Mt. Elgon, Africa , Shaded Relief and Colored Height
Hi-Res. Tiff | Sinai Peninsula, Shaded Relief and Colored Height
Hi-Res. Tiff | Gotel Mtns, Nigeria & Cameroon, SRTM Shaded Relief plus Height as Brightness
View the Africa Image Gallery

Colored Height

PIA04965

This color shaded relief image shows the extent of digital elevation data for Africa recently released by the Shuttle Radar Topography Mission (SRTM). This release includes data for all of the continent, plus the island of Madagascar and the Arabian Peninsula. SRTM flew on board the Space Shuttle Endeavour in February 2000 and used an interferometric radar system to map the topography of Earth's landmass between latitudes 56 degrees south and 60 degrees north.

The data were processed into geographic "tiles," each of which represents one by one degree of latitude and longitude. A degree of latitude measures 111 kilometers (69 miles) north-south, and a degree of longitude measures 111 kilometers or less east-west, decreasing away from the equator. The data are being released to the public on a continent-by-continent basis. This Africa segment includes 3256 tiles, almost a quarter of the total data set. Previous releases covered North America, South America and Eurasia. Forthcoming releases will include Australia plus an "Islands" release for those islands not included in the continental releases. Together these data releases constitute the world's first high-resolution, near-global elevation model. The resolution of the publicly released data is three arcseconds (1/1,200 of a degree of latitude and longitude), which is about 90 meters (295 feet).

Coverage in the current data release extends from 35 degrees north latitude at the southern edge of the Mediterranean to the very tip of South Africa, encompassing a great diversity of landforms. The northern part of the continent consists of a system of basins and plateaus, with several volcanic uplands whose uplift has been matched by subsidence in the large surrounding basins. Many of these basins have been infilled with sand and gravel, creating the vast Saharan lands. The Atlas Mountains in the northwest were created by convergence of the African and Eurasian tectonic plates.

The geography of the central latitudes of Africa is dominated by the Great Rift Valley, extending from Lake Nyasa to the Red Sea, and splitting into two arms to enclose an interior plateau and the nearly circular Lake Victoria, visible in the right center of the image. To the west lies the Congo Basin, a vast, shallow depression which rises to form an almost circular rim of highlands.

Most of the southern part of the continent rests on a concave plateau comprising the Kalahari basin and a mountainous fringe, skirted by a coastal plain which widens out in Mozambique in the southeast.

Many of these regions were previously very poorly mapped due to persistent cloud cover or the inaccessibility of the terrain. Digital elevation data, such as provided by SRTM, are particularly in high demand by scientists studying earthquakes, volcanism, and erosion patterns for use in mapping and modeling hazards to human habitation. But the shape of Earth's surface affects nearly every natural process and human endeavor that occurs there, so elevation data are used in a wide range of applications.

In this index map color-coding is directly related to topographic height, with brown and yellow at the lower elevations, rising through green, to white at the highest elevations. Blue areas on the map represent water within the mapped tiles, each of which includes shorelines or islands.

Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, DC.

Orientation: North toward the top, Mercator projection
Image Data: Colored SRTM elevation model
Date Acquired: February 2000

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Anaglyph of Shaded Relief

PIA04964

This stereoscopic shaded relief image shows Africa's topography as measured by the Shuttle Radar Topography Mission (SRTM) in February 2000. Also shown are Madagascar, the Arabian Peninsula, and other adjacent regions. Previously, much of the topography here was not mapped in detail. Digital elevation data, such as provided by SRTM, are in high demand by scientists studying earthquakes, volcanism, and erosion patterns and for use in mapping and modeling hazards to human habitation. But the shape of Earth's surface affects nearly every natural process and human endeavor that occurs there, so elevation data are used in a wide range of applications. The image shown here is greatly reduced from the original data resolution, but still provides a good overview of the continent's landforms. It is best viewed while panning at full resolution while using image display software.

The northern part of the continent consists of a system of basins and plateaus, with several volcanic uplands whose uplift has been matched by subsidence in the large surrounding basins. Many of these basins have been infilled with sand and gravel, creating the vast Saharan lands. The Atlas Mountains in the northwest were created by convergence of the African and Eurasian tectonic plates.

The geography of the central latitudes of Africa is dominated by the Great Rift Valley, extending from Lake Nyasa to the Red Sea, and splitting into two arms to enclose an interior plateau and the nearly circular Lake Victoria, visible in the right center of the image. To the west lies the Congo Basin, a vast, shallow depression that rises to form an almost circular rim of highlands.

Most of the southern part of the continent rests on a concave plateau comprising the Kalahari Basin and a mountainous fringe, skirted by a coastal plain that widens out in Mozambique in the southeast.

Specific noteworthy features one may wish to explore in this scene include (1) the Richat Structure in Mauritania, a "bull's eye" geologic structure, (2) the Velingara Ring in Senegal, a possible meteorite impact crater, (3) the delta of the Niger River in Nigeria, (4) the Cameroon Line of volcanoes, crossing Cameroon and extending offshore, (5) long linear mountain ridges crossing the southern end of Africa, (6) Mount Kilimanjaro and neighboring volcanoes in Kenya and Tanzania, (7) the Afar Triangle in Ethiopia, Djibouti, and vicinity, where Earth's crust is being pulled in three directions by tectonic forces, (8) the Dead Sea fault line, between Israel and Jordan, (9) ancient shorelines, inland from the coast of Libya, and (10) vast seas of sand dunes, particularly across the Sahara Desert and much of the Arabian Peninsula.

This anaglyph was created by deriving a shaded relief image from the SRTM data, draping it back over the SRTM elevation model, and then generating two differing perspectives, one for each eye. Illumination is from the north (top). When viewed through special glasses, the anaglyph is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter.

Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C.

Orientation: North toward the top, Mercator projection
Image Data: Shaded SRTM elevation model
Date Acquired: February 2000

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Richat Structure, Mauritania, Perspective View, Landsat image over SRTM elevation

PIA04963

This prominent circular feature, known as the Richat Structure, in the Sahara desert of Mauritania is often noted by astronauts because it forms a conspicuous 50-kilometer-wide (30-mile-wide) bull's-eye on the otherwise rather featureless expanse of the desert. Initially mistaken for a possible impact crater, it is now known to be an eroded circular anticline (structural dome) of layered sedimentary rocks.

Extensive sand dunes occur in this region and the interaction of bedrock topography, wind, and moving sand is evident in this scene. Note especially how the dune field ends abruptly short of the cliffs at the far right as wind from the northeast (lower right) apparently funnels around the cliff point, sweeping clean areas near the base of the cliff. Note also the small isolated peak within the dune field. That peak captures some sand on its windward side, but mostly deflects the wind and sand around its sides, creating a sand-barren streak that continues far downwind.

This view was generated from a Landsat satellite image draped over an elevation model produced by the Shuttle Radar Topography Mission (SRTM). The view uses a 6-times vertical exaggeration to greatly enhance topographic expression. For vertical scale, note that the height of the mesa ridge in the back center of the view is about 285 meters (about 935 feet) tall. Colors of the scene were enhanced by use of a combination of visible and infrared bands, which helps to differentiate bedrock (browns), sand (yellow, some white), minor vegetation in drainage channels (green), and salty sediments (bluish whites). Some shading of the elevation model was included to further highlight the topographic features.

Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C.

View Size: 68 kilometers (42 miles) wide by 112 kilometers (69 miles) distance
Location: 21.2 degrees North latitude, 11.7 degrees West longitude
Orientation: View toward west-northwest
Image Data: Landsat Bands 1, 4, 7 in B.G.R.
Date Acquired: February 2000 (SRTM), January 13, 1987 (Landsat)

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Richat Structure, Mauritania, Anaglyph, Landsat image over SRTM elevation

PIA04962

The prominent circular feature seen here, known as the Richat Structure, in the Sahara desert of Mauritania, is often noted by astronauts because it forms a conspicuous 50-kilometer-wide (30-mile-wide) bull's-eye on the otherwise rather featureless expanse of the desert. Initially mistaken for a possible impact crater, it is now known to be an eroded circular anticline (structural dome) of layered sedimentary rocks.

Extensive sand dunes occur in this region and the interaction of bedrock topography, wind, and moving sand is evident in this scene. Note especially how the dune field generally ends abruptly short of the cliffs as wind from the northeast (upper right) apparently funnels around the cliff, sweeping clean areas near the base of the cliff (particularly at the cliff point to the northwest, upper left, of the Richat Structure). Note also the isolated peak within the dune field. That peak captures some sand on its windward side, but mostly deflects the wind and sand around its sides, creating a sand-barren streak that continues far downwind.

To the west (left), a north-south trending bedrock ridge breaks up the sand field, and downwind from the ridge, streaks of dunes occur at certain locations. Upon close inspection, these streaks can be seen to be associated with saddles (low points) along the ridge, where sand preferentially passes over the ridge. This again shows how topographic features control the distribution of sand across the terrain

This anaglyph was created by draping a Landsat reflectance infrared image over an SRTM elevation model, and then generating two differing perspectives, one for each eye. When viewed through special glasses, the anaglyph is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter For vertical scale, note that the prominent cliffs (image center) are about 300 meters (about 1000 feet) tall, the central rings of the Richat structure are about 80 meters (about 260 feet) tall, and the sand dunes rise about 80 meters (about 260 feet) above the adjacent terrain across the center of the image.

Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C.

Size: 174.6 kilometers (108.3 miles) by 112.5 kilometers (69.8 miles)
Location: 21.4 degrees North latitude, 12.0 degrees West longitude
Orientation: North toward the top
Image Data: Landsat band 7
Date Acquired: February 2000 (SRTM), January 13, 1987 (Landsat)

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Cape Town, South Africa, Perspective View, Landsat image over SRTM elevation

PIA04961

Cape Town and the Cape of Good Hope, South Africa, appear in the foreground of this perspective view generated from a Landsat satellite image and elevation data from the Shuttle Radar Topography Mission (SRTM). The city center is located at Table Bay (at the lower left), adjacent to Table Mountain, a 1,086-meter (3,563-foot) tall sandstone and granite natural landmark.

Cape Town enjoys a Mediterranean climate but must deal with the limited water supply characteristic of that climate. Until the 1890s the city relied upon streams and springs along the base of Table Mountain, then built a small reservoir atop Table Mountain to capture and store rainfall there. Now the needs of a much larger population are met in part by much larger reservoirs such as seen here far inland (mid-distance left) at the Theewaterskloof Dam.

False Bay is the large bay to the south (right) of Cape Town, just around the Cape of Good Hope. It is one of the largest bays along the entire South African coast, but nearby Cape Town has its harbor at Table Bay. False Bay got its name because mariners approaching Cape Town from the east would see the prominent bay and falsely assume it to be the entrance to Cape Town harbor. Similarly, people often mistake the Cape of Good Hope as the southernmost point of Africa. But the southernmost point is actually Cape Agulhas, located just to the southeast (upper right) of this scene.

This Landsat and SRTM perspective view uses a 2-times vertical exaggeration to enhance topographic expression. The back edges of the data sets form a false horizon and a false sky was added. Colors of the scene were enhanced by image processing but are the natural color band combination from the Landsat satellite.

Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C.

View Size: 66 kilometers (41 miles) wide by 134 kilometers (83 miles) distance
Location: 34.2 degrees South latitude, 18.7 degrees East longitude
Orientation: View toward east-southeast
Image Data: Landsat Bands 1, 2, 3 in blue, green, red
Date Acquired: February 2000 (SRTM), June 13, 2000 (Landsat)

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Cape Town, South Africa, Anaglyph, Landsat image over SRTM elevation

PIA04960

Cape Town and the Cape of Good Hope, South Africa, appear on the left (west) of this anaglyph view generated from a Landsat satellite image and elevation data from the Shuttle Radar Topography Mission (SRTM). The city center is located between Table Bay (upper left) and Table Mountain (just to the south), a 1,086-meter (3,563-foot) tall sandstone and granite natural landmark.

Cape Town enjoys a Mediterranean climate but must deal with the limited water supply characteristic of that climate. Until the 1890s the city relied upon streams and springs along the base of Table Mountain, then built a small reservoir atop Table Mountain to capture and store rainfall there (visible in this anaglyph when viewed at full resolution). Now the needs of a much larger population are met in part by much larger reservoirs such as seen well inland (upper right) at the Theewaterskloof Dam.

False Bay is the large bay to the southeast (lower right) of Cape Town, just around the Cape of Good Hope. It is one of the largest bays along the entire South African coast, but nearby Cape Town has its harbor at Table Bay. False Bay got its name because mariners approaching Cape Town from the east would see the prominent bay and falsely assume it to be the entrance to Cape Town harbor. Similarly, people often mistake the Cape of Good Hope as the southernmost point of Africa. But the southernmost point is actually Cape Agulhas, located just to the southeast (lower right) of this scene.

This anaglyph was created by draping a Landsat visible light image over an SRTM elevation model, and then generating two differing perspectives, one for each eye. When viewed through special glasses, the anaglyph is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter.

Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C.

View Size: 66 kilometers (41 miles) by 134 kilometers (83 miles)
Location: 34.2 degrees South latitude, 18.7 degrees East longitude
Orientation: North-northeast at top
Image Data: Landsat Bands 1, 2, 3 merged as grey
Date Acquired: February 2000 (SRTM), June 13, 2000 (Landsat)

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Olduvai, Gorge, Shaded Relief and Colored Height

PIA04959

Three striking and important areas of Tanzania in eastern Africa are shown in this color-coded shaded relief image from the Shuttle Radar Topography Mission. The largest circular feature in the center right is the caldera, or central crater, of the extinct volcano Ngorongoro. It is surrounded by a number of smaller volcanoes, all associated with the Great Rift Valley, a geologic fault system that extends for about 4,830 kilometers (2,995 miles) from Syria to central Mozambique.

Ngorongoro's caldera is 22.5 kilometers (14 miles) across at its widest point and is 610 meters (2,000 feet) deep. Its floor is very level, holding a lake fed by streams running down the caldera wall. It is part of the Ngorongoro Conservation Area and is home to over 75,000 animals. The lakes south of the crater are Lake Eyasi and Lake Manyara, also part of the conservation area.

The relatively smooth region in the upper left of the image is the Serengeti National Park, the largest in Tanzania. The park encompasses the main part of the Serengeti ecosystem, supporting the greatest remaining concentration of plains game in Africa including more than 3,000,000 large mammals. The animals roam the park freely and in the spectacular migrations, huge herds of wild animals move to other areas of the park in search of greener grazing grounds (requiring over 4,000 tons of grass each day) and water.

The faint, nearly horizontal line near the center of the image is Olduvai Gorge, made famous by the discovery of remains of the earliest humans to exist. Between 1.9 and 1.2 million years ago a salt lake occupied this area, followed by the appearance of fresh water streams and small ponds. Exposed deposits show rich fossil fauna, many hominid remains and items belonging to one of the oldest stone tool technologies, called Olduwan. The time span of the objects recovered dates from 2,100,000 to 15,000 years ago.

Two visualization methods were combined to produce the image: shading and color coding of topographic height. The shade image was derived by computing topographic slope in the northwest-southeast direction, so that northwest slopes appear bright and southeast slopes appear dark. Color coding is directly related to topographic height, with green at the lower elevations, rising through yellow and tan, to white at the highest elevations.

Elevation data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect 3-D measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter (approximately 200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between NASA, the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C.

Location: 3 degrees south latitude, 35 degrees east longitude
Orientation: North toward the top, Mercator projection
Size: 223 by 223 kilometers (138 by 138 miles)
Image Data: shaded and colored SRTM elevation model
Date Acquired: February 2000

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Mt. Elgon, Africa , Shaded Relief and Colored Height

PIA04958

The striking contrast of geologic structures in Africa is shown in this shaded relief image of Mt. Elgon on the left and a section of the Great Rift Valley on the right.

Mt. Elgon is a solitary extinct volcano straddling the border between Uganda and Kenya, and at 4,321 meters (14,178 feet) tall is the eighth highest mountain in Africa. It is positioned on the Pre-Cambriam bedrock of the Trans Nzoia Plateau, and is similar to other such volcanoes in East Africa in that it is associated with the formation of the Rift Valley. However one thing that sets Mt. Elgon apart is its age.

Although there is no verifiable evidence of its earliest volcanic activity, Mt. Elgon is estimated to be at least 24 million years old, making it the oldest extinct volcano in East Africa. This presents a striking comparison to Mt. Kilimanjaro, the highest mountain in Africa at 5,895 meters (19,341 feet), which is just over one million years old. Judging by the diameter of its base, it is a common belief among geological experts that Mt. Elgon was once the highest mountains in Africa, however erosion has played a significant role in reducing the height to its present value.

Juxtaposed with this impressive mountain is a section of the Great Rift Valley, a geological fault system that extends for about 4,830 kilometers (2,995 miles) from Syria to central Mozambique. Erosion has concealed some sections, but in some sections like that shown here, there are sheer cliffs several thousand feet high. The present configuration of the valley, which dates from the mid-Pleistocene epoch, results from a rifting process associated with thermal currents in the Earth's mantle.

Two visualization methods were combined to produce the image: shading and color coding of topographic height. The shade image was derived by computing topographic slope in the northwest-southeast direction, so that northwest slopes appear bright and southeast slopes appear dark. Color coding is directly related to topographic height, with green at the lower elevations, rising through yellow and tan, to white at the highest elevations.

Elevation data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect 3-D measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter (approximately 200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between NASA, the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C.

Location: 1 degree north latitude, 35 degrees east longitude
Orientation: North toward the top, Mercator projection
Size: 223 by 223 kilometers (138 by 138 miles)
Image Data: shaded and colored SRTM elevation model
Date Acquired: February 2000

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Sinai Peninsula, Shaded Relief and Colored Height

PIA04957

The Sinai Peninsula, located between Africa and Asia, is a result of those two continents pulling apart from each other. Earth's crust is cracking, stretching, and lowering along the two northern branches of the Red Sea, namely the Gulf of Suez, seen here on the west (left), and the Gulf of Aqaba, seen to the east (right). This color-coded shaded relief image shows the triangular nature of the peninsula, with the coast of the Mediterranean Sea forming the northern side of the triangle. The Suez Canal can be seen as the narrow vertical blue line in the upper left connecting the Red Sea to the Mediterranean.

The peninsula is divided into three distinct parts; the northern region consisting chiefly of sandstone, plains and hills, the central area dominated by the Tih Plateau, and the mountainous southern region where towering peaks abound. Much of the Sinai is deeply dissected by river valleys, or wadis, that eroded during an earlier geologic period and break the surface of the plateau into a series of detached massifs with a few scattered oases.

Two visualization methods were combined to produce the image: shading and color coding of topographic height. The shade image was derived by computing topographic slope in the northwest-southeast direction, so that northwest slopes appear bright and southeast slopes appear dark. Color coding is directly related to topographic height, with green at the lower elevations, rising through yellow and tan, to white at the highest elevations.

Elevation data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect 3-D measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter (approximately 200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between NASA, the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise,Washington, D.C.

Location: 30 degrees north latitude, 34 degrees east longitude
Orientation: North toward the top, Mercator projection
Size: 289 by 445 kilometers (180 by 277 miles)
Image Data: shaded and colored SRTM elevation model
Date Acquired: February 2000

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Gotel Mtns, Nigeria & Cameroon, SRTM Shaded Relief plus Height as Brightness

River drainage patterns provide clues to the rock types and erosional processes involved in landscape evolution. Here in the Gotel Mountains along the border between Nigeria and Cameroon two distinct and highly contrasting patterns are evident. The lowlands in the northern and northwestern parts of the scene exhibit "dendritic" patterns, while the highlands in the southern and southeastern parts of the scene show "rectangular" and other linear drainage patterns.

Dendritic drainage patterns appear almost random. Moving upstream, streams split into smaller and smaller channels, with finer and finer spacing, and they show little preference for map orientation other than to complete the pattern. In contrast, rectangular and other linear drainage patterns show a distinct preference for certain orientations in map view. In this scene, the two major preferred orientations are rotated slightly clockwise of north-south and east-west.

Linear drainage patterns usually match the cracking patterns that can occur in relatively hard rocks, including igneous rocks such as granite and basalt. Stream erosion typically follows such lines of weakness in these hard rocks. Meanwhile, the randomness of dendritic patterns indicates that no such cracks nor any other geologic structure controls the erosion where that pattern occurs.

Given the above, the topographic pattern in this scene appears to tell us the following about the geology of this location. The lowlands are composed of poorly consolidated (relatively soft) rocks or sediments that are at least 100 meters (330 feet) thick and are "massive" (uniform, with no prominent layering at the observed scale). The randomness of the dendritic patterns further indicates that stream erosion is the only significant dynamic process altering the lowland landscape. Forces such as volcanism and tectonics are not altering these landforms.

Meanwhile, the neighboring highlands are composed of crystalline rocks, such as granite, that are very hard (generally resistant to erosion) and probably very old. Sometime through their history these rocks cracked, perhaps when they cooled, perhaps under tectonic stress, or perhaps when pressure upon them was relieved when they were unearthed by erosion. Now at the surface, these cracks are zones of weakness as these hard rocks otherwise resist stream erosion.

But while the topographic data gives clues, it does not always provide definitive answers. Are the lowlands made up of soft sediments washed in from elsewhere or are they simply rocks "softened" by weathering (disintegration into sand) in place over time. If the latter, might they in fact have been granite also? The two patterns interfinger geographically, suggesting that the rugged highlands may be evolving into the dendritic lowlands. Weathering products (loose sands) tend to accumulate in place in low relief terrain because erosion there is slow to remove them. Also, granites are typically "massive" and cracking patterns vanish when the rocks disintegrate. The topographic data indeed provide thought provoking evidence, but definitive answers will require fieldwork or other additional evidence.

This image was created directly from an SRTM elevation model. A shade image was derived by computing topographic slope in the north-south direction. Northern slopes appear bright and southern slopes appear dark. The shade image was then merged with a height-as-brightness image, which helps clarify the continuity of the drainage networks.

Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C.

Size: 144.8 kilometers (89.8 miles) by 131.5 kilometers (81.5 miles)
Location: 7 degrees North latitude, 10 degrees East longitude
Orientation: North toward the top
Image Data: SRTM elevation shaded plus height-as-brightness
Date Acquired: February 2000

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