To check, we need one single event which has been dated by several methods. A nice example is the Triassic multiple-impact event, which formed a 4500-kilometer-long chain of huge craters. (There must have been a train of big objects from space, which hit the spinning earth, one by one, across several hours. Much like the way comet Shoemaker-Levy hit Jupiter in 1994.)
Here are the five confirmed craters:
|Crater||Country||Diameter||Million Years Ago||Dating Method|
|Manicouagan||Canada||100 km||214 ± 1||U-Pb on zircons|
|Saint Martin||Canada||40 km||219 ± 32||Rb/Sr|
|Rochechouart||France||25 km||214 ± 8||Ar/Ar laser spot fusion|
|Obolon||Ukraine||15 km||215 ± 25||stratigraphic|
|Red Wing||USA||9 km||200 ± 25||stratigraphic|
"Stratigraphic" dating means that the crater itself has not been dated. Instead, the rock strata above and below the crater was dated. (By now, the Red Wing crater is under 1.5 kilometers of sediment.)
The table shows five datings that are consistent with each other. However, there is a sixth dating involved: the one for drawing the map.
Today, the continents are moving about one inch a year. This is a simple fact which can be measured by anyone with good GPS equipment. So, in 214 million years, the continents could have moved three thousand miles. To get a map of that past world, geologists did K/Ar datings of ancient lava flows. As the article below shows, the three main craters form a dead straight line on that map.
These dates were obtained by several different radioactive methods, on rocks of several different kinds, by geologists from four different countries. But the dates are consistent. That is the usual case, so the article didn't bother to comment on it.
For more detail:
Evidence for a late Triassic multiple impact event on Earth, J. Spray, S. Kelley, and D. Rowley, Nature 392,171-173 (12 March 1998)
Paleographic Atlas Project: Pictures related to the Multi-Impact Event