Media Information
 
 
 
Collection:
NASA Planetary Photo Journal Collection
Title:
Shaded Relief with Height as Color, North America
Original Caption Released with Image:
This image of North America was generated with data from the Shuttle Radar Topography Mission (SRTM). For this broad view the resolution of the data was first reduced to 30 arcseconds (about 928 meters north-south and 736 meters east-west in central North America), matching the best previously existing global digital topographic data set called GTOPO30. The data were then resampled to a Mercator projection with approximately square pixels (about one kilometer, or 0.6 miles, on each side). Even at this decreased resolution the variety of landforms comprising the North American continent is readily apparent.

Active tectonics (structural deformation of the Earth's crust) along and near the Pacific -- North American plate boundary creates the great topographic relief seen along the Pacific coast. Earth's crustal plates converge in southern Mexico and in the northwest United States, melting the crust and producing volcanic cones. Along the California coast, the plates are sliding laterally past each other, producing a pattern of slices within the San Andreas fault system. And, where the plates are diverging, the crust appears torn apart as one huge tear along the Gulf of California (northwest Mexico), and as the several fractures comprising the Basin and Range province (in and around Nevada).

Across the Great Plains, erosional patterns dominate, with streams channels surrounding and penetrating the remnants of older smooth slopes east of the Rocky Mountains. This same erosion process is exposing the bedrock structural patterns of the Black Hills in South Dakota and the Ozark Mountains in Arkansas. Lateral erosion and sediment deposition by the Mississippi River has produced the flatlands of the lower Mississippi Valley and the Mississippi Delta.

To the north, evidence of the glaciers of the last ice age is widely found, particularly east of the Canadian Rocky Mountains and around the Great Lakes. From northeastern British Columbia, across Alberta, Saskatchewan, and Manitoba to North Dakota and Minnesota, huge striations clearly show the flow pattern of the glaciers. And southwest of Lakes Michigan, Huron, and Erie, arcing ridges of sediment, called terminal moraines, show where glaciers dumped sediment at their melting ends.

In eastern Canada, New York, and New England, the terrain has been scoured by glaciers, and eroded by streams, particularly along fractures in the bedrock. In Labrador and Quebec, the Mistastin, Manicougan, and Clearwater Lakes meteor impact craters can also be seen. Further south, narrow curving ridges of upturned and eroded layered rocks form most of the Appalachian Mountains. In contrast, around the Caribbean Sea region (Yucatan, Florida, and the Bahamas), flat-lying, stable limestone platforms are common, while the most eastern islands of the Caribbean include active volcanoes along another convergence zone of tectonic plates.

Two visualization methods were combined to produce the image: shading and color coding of
Original Caption Released with Image:
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 Imagery and Mapping Agency (NIMA) 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: 15 to 60 degrees North latitude, 50 to 130 degrees West longitude
Orientation: North toward the top, Mercator projection
Image Data: shaded and colored SRTM elevation model
Original Data Resolution: SRTM 1 arcsecond (about 30 meters or 98 feet)
Date Acquired: February 2000
Produced By:
JPL
Mission:
Shuttle Radar Topography Mission (SRTM)
Spacecraft:
Space Shuttle Endeavour
Target Name:
Earth
Is a satellite of:
Sol (our sun)
Instrument:
C-Band Interferometric Radar
Product Size:
9600 samples x 7240 lines
facet_what:
Sun
facet_what:
Earth
facet_what:
C/X-Band Synthetic Aperture Radar
facet_what:
Spaceborne Imaging Radar
facet_what:
Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar
facet_what:
Space Shuttle Endeavour
facet_what:
Shuttle Radar Topography Mission
facet_what:
SRTM
facet_what:
C-Band Interferometric Radar
facet_what:
Space Shuttle Orbiter
facet_what:
Columbia
facet_where:
Jet Propulsion Laboratory
facet_where:
California
facet_where:
Washington
facet_where:
Florida
facet_where:
Canada
facet_where:
Mississippi
facet_where:
Nevada
facet_where:
South Dakota
facet_where:
New York
facet_where:
Arkansas
facet_where:
Michigan
facet_where:
Caribbean Sea
facet_where:
Minnesota
facet_where:
Bahamas
facet_where:
Gulf of California
facet_where:
North Dakota
facet_where:
Jet Propulsion Laboratory (JPL)
facet_where:
Washington, D.C.
facet_where:
United States of America
facet_when:
1994
facet_when:
February 2000
facet_when_year:
1994
facet_when_year:
2000
Image #:
PIA03377
UID:
SPD-PHOTJ-PIA03377
orignial url:
http://photojournal…

Shaded Relief with Height as Color, North America
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