Two basic types of dating are possible: absolute and relative. estimation of accurate absolute ages from crater densities on the terrestrial planets. On Mars , the analysis indicates that volcanism and plains formation Another method that has been used successfully on the Moon to estimate absolute ages involves the. How is crater density used in the relative dating feature on the moon? The greater the What surface features does Mars have that are also common on Earth?. the relative ages of the two surfaces (e.g. one area is twice as old as another). determine how the crater density is related to the absolute age at these sites. Now, at least for consisted of launches of two separate spacecraft to Mars. and returning images used for landing site selection, the orbiter and lander detached.
Impact craters are ubiquitous throughout the solar system — every single solid body has craters on its surface except for the moon Io because its surface is so young due to the incredible amounts of vulcanism.
Impact craters form when an impactor — like an asteroid or comet — hits the target surface of a planet or moon. The impact occurs at high speed, and the final crater depth, diameter, and shape are effectively determined by the surface gravity, the mass of the impactor, and the velocity of the impactor. There are craters of other origins, such as pit craters or caldera craters at the top of volcanoes.
But if that surface were to have something happen to it, like it got covered by lava, then that would erase the craters and the crater age would be set back to 0.
We count the number of craters of different sizes for a part of the surface and then compare that with the rate of impacts of that size. To actually calibrate the number of impactors of a given size to an absolute age requires us to date the rocks within that surface. This can then be extrapolated to other locations in the solar system.
Craters form in all sizes — from microcraters on airless bodies like the moon to giant basins literally s of kilometers across. In general, researchers use craters that are on the 10s of meters scale to about 1 kilometer, or a few kilometers to a few 10s of kilometers for age dating at present, there is a general mismatch gap in what is used; this is generally because the meter-scale craters are used to date smaller, isolated surface areas whereas kilometer-scale craters are used to date much larger geologic units that cover a significant percentage of the planet or moon.
One more piece of background information is that when craters form, they send up clouds of debris, from dust-sized particles to objects up to a few percent the size of the original impactor.
These larger chunks of material are ejected outwards from the forming crater, and they may end up forming their own craters. Secondary craters are different from primary craters in the way they look because of their formation history — mainly they are much smaller and they are also shallower.
How is crater density used in the relative dating of features on the moon
This is both because the ejected material that formed them was much smaller than the original impactor and because the velocity of the debris is much less than the original impactor, so there is significantly less energy to form the secondary crater.
In addition, secondary craters that form closest to the primary within about 10 crater radii are usually very easy to identify as secondary due to the way they look and the surrounding surface. But the Moon had no atmosphere and it cooled a lot quicker than the Earth did, because it was smaller.
Once the Solar System got to a point that it wasn't "swimming" in a cloud of debris, we basically had the nine planets left as the survivors of this early bombardment. This left the Moon scarred with all kinds of impact craters which would be the oldest craters we see today. Finally there came a point where most of the larger rocks asteroids floating around had been absorded by the planets, and this left just the smaller chunks of rock.
How is crater density used in the relative dating of features on the moon? | Yahoo Answers
This is the start of the second phase of cratering where most of this remaining debris eventually was "sucked up" by the Earth and Moon and planets. This second phase ended about 3 billion years ago. The third phase we are still in today with occasional impacts occuring, but nothing like the first two stages.
So how does this answer your question????? Let's just concentrate on the Moon now: Imagine the Moon early in the first phase just covered with shoulder to shoulder craters.
How is crater density used in the relative dating of features on the moon?
Each new crater formed over the top of older ones. In other words, when you see a large crater today that has smaller ones inside it, you know that the large impact had to occur before the smaller ones. If this wasn't true, the larger crater would have wiped out any evidence of the smaller ones, right?Overview of JMARS crater counting lab
Then there came the point when the lava I mentioned earlier covered up the lower impact basins we see today as the "Man on the Moon. Impacts still happened on the plains, but nothing like in the first phase of cratering.
So you can begin to see that the older an area on the Moon is, the larger the crater density. That plot of ground was around when the first phase of cratering was still going on. It's covered with crater after crater of different sizes with no smooth, craterless areas at all! The only other "weathering" that existed on the lunar surface today is a constant bombardment of very small impacts with an occasional larger one.
This is especially true during meteor showers here on Earth. We see a "shooting star" which is a sand sized grain of ice or rock hitting our atmosphere at 50 miles a second or so.