The suspicion that the crater is only 50,000 years old, giver or take about 3,000 years, comes from the fact that it is not terribly weathered. Anything over 100,000 years would be much more worn down or even obliterated.
Fortunately, the climate is fairly dry in that area, so the weathering influence comes mainly from the action of wind and sand, and not so much from rain, which can do much more damage to such a site.
In short, the age determination is rough, and more a process of elimination: no more than 100,000 years, and no less than 20,000 (and certainly more than 6,000 years) based on the amount of weathering and the amount of debris buildup in the bottom of the crater.
Hope this helps.
Thanks for the reply.
So it's nothing more than an educated guess. And the failure to account for a global flood and/or it's aftermath, or even a bad projection in sediment rates could cause 50,000 to be a bad date.
But then wouldn't the Flood have filled it with silt? < /thumper>