Return to Earth From Space Home
Earth from Space logo Image Information Earth from Space logo

Display a Screen Layout for Printing

IMAGE: gray corner       IMAGE: gray corner
  Image: Geographic Location Direction Photo #: ISS017-E-13789 Date: Aug. 2008
Geographic Region: LIBYA
Feature: DESERT, DENDRITIC DRAINAGE

Ordering information for space photography
 
IMAGE: gray corner     IMAGE: gray corner

Image: gray corner     Image: gray corner
  View Low-Resolution Image  
  Desert Erosion, A Modern Libyan Landscape

This detailed astronaut photograph shows the classic patterns of an eroded desert landscape, about 300 kilometers (190 miles) south of Libya’s Mediterranean coast. Widespread indented patterns are low escarpments and stream terraces generated by stream erosion—on those few occasions in any decade when enough rain falls for streams to flow. The only areas where sediment is being deposited are the streambeds, which appear in this image as sinuous zones with a distinct component of black minerals. These minerals give the streambeds a darker color than adjacent low escarpments (image top left and lower left). The sediment comes from a volcanic landscape immediately upstream to the west.

Other stream-generated features are several relict stream banks (indicated by ovals); one area even preserves both (parallel) banks of the original stream (far right oval). The ancient stream banks were cemented by minerals such as calcium carbonate and gypsum, introduced by the streams when they were active, probably during wetter climates in the past 2 million years. Relict stream courses show prior positions of streams, and help tell the region’s paleoclimate story. They also provide Earth analogs for similar features on Mars.

The lack of vegetation is the first indication of the great aridity of the region, but sand dunes also appear as sinuous lines oriented perpendicular to the dominant northeasterly wind direction (transverse dunes). If the dominant wind direction remains the same, these transverse dunes would be expected to move further to the southwest over time (towards the top left). Some of the dunes cross the river courses, showing how seldom the rivers flow.
 
Image: gray corner     Image: gray corner

Images: All Available Images Low-Resolution 333k
Mission: ISS017  
Roll - Frame: E - 13789
Geographical Name: LIBYA  
Features: DESERT, DENDRITIC DRAINAGE  
Center Lat x Lon: 28.3N x 16.2E
Film Exposure:   N=Normal exposure, U=Under exposed, O=Over exposed, F=out of Focus
Percentage of Cloud Cover-CLDP: 10
 
Camera: N2
 
Camera Tilt: 24   LO=Low Oblique, HO=High Oblique, NV=Near Vertical
Camera Focal Length: 400  
 
Nadir to Photo Center Direction: SW   The direction from the nadir to the center point, N=North, S=South, E=East, W=West
Stereo?:   Y=Yes there is an adjacent picture of the same area, N=No there isn't
Orbit Number: 3851  
 
Date: 20080819   YYYYMMDD
Time: 143609   GMT HHMMSS
Nadir Lat: 29.5N  
Latitude of suborbital point of spacecraft
Nadir Lon: 17.0E  
Longitude of suborbital point of spacecraft
Sun Azimuth: 264   Clockwise angle in degrees from north to the sun measured at the nadir point
Space Craft Altitude: 191   nautical miles
Sun Elevation: 36   Angle in degrees between the horizon and the sun, measured at the nadir point
Land Views: DESERT, EROSION  
Water Views: SEDIMENT  
Atmosphere Views:  
Man Made Views:  
City Views:  
Photo is not associated with any sequences


NASA Human
Space Flight
NASA
Home Page
JSC
Home Page
NASA
Image eXchange
JSC Digital
Image Collection
Earth Sciences &
Image Analysis