Many layers are present in the wall of Eratosthenian-Age crater Euler, in south Mare Imbrium (23.3°N, 330.8°E). The layers are interpreted to be individual lava flows that formed the lunar maria prior to the crater's formation. LROC Narrow Angle Camera (NAC) observation M124763045LE, LRO orbit 3530, April 1, 2010, image field of view is 500 meters. View the full LROC Featured Image HERE [NASA/GSFC/Arizona State University].
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Euler crater is located in Mare Imbrium (23.2°N, 330.8°E) and named for the 18th century mathematician. Mare Imbrium is one of the lunar basins that was filled with floods of basalt. But how were these mare deposits emplaced? Because the impact cratering process can often expose the underlying geology, impact craters are a great place to search for clues to how the basalts were emplaced. However, the post-impact processes that occur, such as mass wasting and slumping of crater walls, undermines this ability over time.
LROC Wide Angle Camera (WAC) monochrome mosaic context image of Euler crater; The LROC Featured Image release August 2, 2011 is framed by the white box. (Euler crater is 29 kilometers in diameter.) View the full-sized LROC Featured Image WAC context HERE [NASA/GSFC/Arizona State University].
Euler is a familiar landmark crater through moderate magnification from Earth, in stark relief as the sunrise terminator passes over Mare Imbrium, about 2 days following First Quarter. In full sunlight, as seen in one of seven bands swept up by the LROC WAC above, a variety of other features come into view. The stream of secondary crater saturation, from the east side of Euler to the north, in the image above is radiant from the Copernicus impact, 480 kilometers to the southeast. LROC WAC observation M140093923CE (604nm); LRO orbit 5779, September 25, 2010; resolution 63.4 meters per pixel, solar illumination incidence angle 23.54° [NASA/GSFC/Arizona State University].
Luckily for us, Euler crater is fresh enough that it still has exposed layers of Mare Imbrium. We can even measure the thickness of individual layers, and many are between 3 and 12 m. The layers reveal that the lunar maria were deposited as many thin individual flood lava flows. Similar processes formed the Columbia River Basalts on Earth. Several other craters in the lunar maria exhibit layering, as do the pit craters. These observations all reinforce the lava flow interpretation.
How many layers can you count in the full NAC frame?
Layering in Messier A
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