Difference between revisions of "February 11, 2011"
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=How Old is That Mare?= | =How Old is That Mare?= | ||
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<em>left image from [http://www.lpi.usra.edu/meetings/lpsc2011/pdf/2179.pdf Hiesinger, van der Bogert, Reiss and Robinson]; right LRO LOLA data processed by [mailto:mauricejscollins@hotmail.com Maurice Collins]</em><br /> | <em>left image from [http://www.lpi.usra.edu/meetings/lpsc2011/pdf/2179.pdf Hiesinger, van der Bogert, Reiss and Robinson]; right LRO LOLA data processed by [mailto:mauricejscollins@hotmail.com Maurice Collins]</em><br /> | ||
<br /> | <br /> | ||
| − | The answer to the title question is, "It depends on where you are." Like all maria, Mare Crisium is a vast pile of lava that was | + | The answer to the title question is, "It depends on where you are." Like all maria, Mare Crisium is a vast pile of lava that was |
| − | erupted over a considerable period of time. Harry Hiesinger and colleagues have used LRO WAC mosaics to count impact | + | erupted over a considerable period of time. Harry Hiesinger and colleagues have used LRO WAC mosaics to count impact |
| − | craters to estimate ages for different parts of Mare Crisium (left). The oldest crater-dated lavas are 3.6 billion years old, and | + | craters to estimate ages for different parts of Mare Crisium (left). The oldest crater-dated lavas are 3.6 billion years old, and |
| − | the youngest seen are 2.7 b.y. Of course, ages can only be obtained for lavas that are still visible; we have no evidence of the | + | the youngest seen are 2.7 b.y. Of course, ages can only be obtained for lavas that are still visible; we have no evidence of the |
| − | ages for the earliest Crisium eruptions whose lavas are probably completely buried in the center of the basin. It might be | + | ages for the earliest Crisium eruptions whose lavas are probably completely buried in the center of the basin. It might be |
| − | expected - as at Serenitatis - that younger lavas filled the middle of the basin, the lowest area, and older lavas are only visible | + | expected - as at Serenitatis - that younger lavas filled the middle of the basin, the lowest area, and older lavas are only visible |
| − | around the edges where they were too elevated to be covered. That is partially true here, with old ages of 3.61, 3.50, 3.60 and | + | around the edges where they were too elevated to be covered. That is partially true here, with old ages of 3.61, 3.50, 3.60 and |
| − | 3.59 b.y. occurring along the west, north, east and southeast shores. But ages of 3.4 to 3.5 b.y. are visible in a broad swath | + | 3.59 b.y. occurring along the west, north, east and southeast shores. But ages of 3.4 to 3.5 b.y. are visible in a broad swath |
| − | across the center from north to south. And young ages of about 3.0 b.y. occur along the south, east and northeast edges, with an | + | across the center from north to south. And young ages of about 3.0 b.y. occur along the south, east and northeast edges, with an |
| − | east-west band of 2.8 to 3.0 b.y. crossing the mare center. I placed one of Maurice Collins' visualizations of LRO altimetry data | + | east-west band of 2.8 to 3.0 b.y. crossing the mare center. I placed one of Maurice Collins' visualizations of LRO altimetry data |
| − | on the right to look for possible correlations of age groups with topography. But there are no consistent correlations. These | + | on the right to look for possible correlations of age groups with topography. But there are no consistent correlations. These |
| − | unsatisfying results demonstrate that the Moon often fails to abide by our simple models of how it should work. This gives an | + | unsatisfying results demonstrate that the Moon often fails to abide by our simple models of how it should work. This gives an |
| − | added meaning to Heinlein's comment that the The Moon is a Harsh Mistress. | + | added meaning to Heinlein's comment that the The Moon is a Harsh Mistress. |
<br /> | <br /> | ||
<em>[mailto:tychocrater@yahoo.com Chuck Wood]</em><br /> | <em>[mailto:tychocrater@yahoo.com Chuck Wood]</em><br /> | ||
<br /> | <br /> | ||
<strong>Related Links</strong><br /> | <strong>Related Links</strong><br /> | ||
| − | Rükl plate [ | + | Rükl plate [https://the-moon.us/wiki/R%C3%BCkl_27 27]<br /> |
Hiesinger, van der Bogert, Reiss and Robinson] (2011) [http://www.lpi.usra.edu/meetings/lpsc2011/pdf/2179.pdf Crater size-frequency distribution measurements of Mare Crisium], <br /> | Hiesinger, van der Bogert, Reiss and Robinson] (2011) [http://www.lpi.usra.edu/meetings/lpsc2011/pdf/2179.pdf Crater size-frequency distribution measurements of Mare Crisium], <br /> | ||
42nd Lunar and Planetary Science Conference<br /> | 42nd Lunar and Planetary Science Conference<br /> | ||
<br /> | <br /> | ||
<hr /> | <hr /> | ||
| + | <p><b>Yesterday's LPOD:</b> [[February 10, 2011|A Basin Quest]] </p> | ||
| + | <p><b>Tomorrow's LPOD:</b> [[February 12, 2011|Egyptian Moon]] </p> | ||
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Latest revision as of 18:46, 13 October 2018
How Old is That Mare?
left image from Hiesinger, van der Bogert, Reiss and Robinson; right LRO LOLA data processed by Maurice Collins
The answer to the title question is, "It depends on where you are." Like all maria, Mare Crisium is a vast pile of lava that was
erupted over a considerable period of time. Harry Hiesinger and colleagues have used LRO WAC mosaics to count impact
craters to estimate ages for different parts of Mare Crisium (left). The oldest crater-dated lavas are 3.6 billion years old, and
the youngest seen are 2.7 b.y. Of course, ages can only be obtained for lavas that are still visible; we have no evidence of the
ages for the earliest Crisium eruptions whose lavas are probably completely buried in the center of the basin. It might be
expected - as at Serenitatis - that younger lavas filled the middle of the basin, the lowest area, and older lavas are only visible
around the edges where they were too elevated to be covered. That is partially true here, with old ages of 3.61, 3.50, 3.60 and
3.59 b.y. occurring along the west, north, east and southeast shores. But ages of 3.4 to 3.5 b.y. are visible in a broad swath
across the center from north to south. And young ages of about 3.0 b.y. occur along the south, east and northeast edges, with an
east-west band of 2.8 to 3.0 b.y. crossing the mare center. I placed one of Maurice Collins' visualizations of LRO altimetry data
on the right to look for possible correlations of age groups with topography. But there are no consistent correlations. These
unsatisfying results demonstrate that the Moon often fails to abide by our simple models of how it should work. This gives an
added meaning to Heinlein's comment that the The Moon is a Harsh Mistress.
Chuck Wood
Related Links
Rükl plate 27
Hiesinger, van der Bogert, Reiss and Robinson] (2011) Crater size-frequency distribution measurements of Mare Crisium,
42nd Lunar and Planetary Science Conference
Yesterday's LPOD: A Basin Quest
Tomorrow's LPOD: Egyptian Moon
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