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Basalt Cliffs, Patagonia, Argentina
This page contains archived content and is no longer being updated. At the time of publication, it represented the best available science. However, more recent observations and studies may have rendered some content obsolete.
Basalt cliffs along the northwest edge of the Meseta de Somuncura
plateau near Sierra Colorada, Argentina show an unusual and striking
pattern of erosion. Stereoscopic observation helps to clarify the
landform changing processes active here. Many of the cliffs appear to be
rock staircases that have the same color as the plateau's basaltic
caprock. Are these the edges of lower layers in the basalt, or are they a
train of slivers that are breaking off from, then sliding downslope and
away from, the caprock? They appear to be the latter. Close inspection
shows that each stair step is too laterally irregular to be a continuous
sheet of bedrock like the caprock. Also, the steps are not flat but
instead are little ridges, as one might expect from broken, tilted, and
sliding slices of the caprock. Stream erosion has cut some gullies into
the cliffs and green vegetation shows that water springs from and flows
down some channels, but landsliding is clearly a major agent of erosion
Landsat satellites have provided visible light and infrared images of
the Earth continuously since 1972. SRTM topographic data match the
30-meter (99-foot) spatial resolution of most Landsat images and provide
a valuable complement for studying the historic and growing Landsat data
archive. The Landsat 7 Thematic Mapper image used here (top image) was provided to
the SRTM project by the United States Geological Survey, Earth Resources
Observation Systems (EROS) Data Center, Sioux Falls, South Dakota.
This anaglyph (lower image) was generated by first draping a Landsat Thematic Mapper
image over a topographic map from the Shuttle Radar Topography Mission,
then producing the two differing perspectives, one for each eye. When
viewed through special glasses, the result 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 the right eye with a
Elevation data used in the lower 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 Imagery and Mapping Agency (NIMA) 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,
CA, for NASA's Earth Science Enterprise, Washington, DC.
Size: 49 kilometers (30 miles) x 29 kilometers (18 miles)
Location: 41 deg. South lat., 67.4 deg. West lon.
Orientation: North toward upper left
Image Data: Landsat bands 1,4,7 (blue, near infrared, short wave infrared) in blue, green, red
Date Acquired: February 19, 2000 (SRTM), January 22, 2000 (Landsat)
For more information, visit the SRTM
site and the Landsat 7 site.