Passage Discussion

[LSAT-Chang]

For some reason, I'm seeing two way different statements that contradict each other in lines 48-54. It first says Lichenometry can accurately date an earthquake to within 10 years... and then it says that Lichenometry is best used for earthquakes that occurred within the last 500 years. I thought they just said it can only date earthquakes that happened within 10 years so how can they all of sudden claim that it is best used for earthquakes that happened in the last 500 years?? Am I misreading something???

[noah]

Dating something within 10 years is referring to the margin of error. Using lichenometry, one could say that a rock is 453-463 years old, for example.

Best used for earthquakes within the last 500 years mean that lichenometry is most useful for earthquakes that happened from about 1500 onwards (and, within that time period, one can get results accurate to about 10 years).

For any future forum readers, here's my passage map:

P1: radiocarbon used to date earthquakes

P2: new method: lichenometry. How it works (measuring rate of lichen spread on rocks affected by earthquakes).

P3: why lichenometry is better. Some caveats to its use.

Scale: for dating of earthquakes:

radiocarbon vs. lichenometry

And, this might be the last time in a long while that I type "lichenometry!"