Impact Cratering Lecture 16

1
Impact Cratering Lecture 16

• Impact Crater Populations

2
Many landscapes in the solar system are dominated
by impact craters---and only impact craters
3
Crater populations are best represented on a
cumulative plot of number vs. size
4
Bob Strom invented the Relative R-plot to
highlight differences in population
5
The size vs number of primary impactors in the
Earth-Moon system is still a matter of some
contention
6
(No Transcript)
7
Simplest idea Growth of a population of
craters, all of the same size
8
For a primary population steeper than the
saturation distribution, population evolution is
simple
9
Observations do support this growth, at least for
small craters on the Moon
10
The level of saturation depends somewhat on the
crater population distribution
11
(No Transcript)
12
Things are much less simple for populations in
which the production population is steeper than
the saturation line
13
Chapman and Mckinnon found that the primary
population shape can show through even heavy
bombardment
14
Regolith depth vs age grows with time according
to a law depending on the primary crater size
distribution
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)