In the early Holocene sediments of southwest Montana’s Red Rock River Valley, there are numerous oval craters which are oriented southwest to northeast at about 24 degrees. If we look back to the southwest, in the direction they came from, we can find similar craters, and airburst morphology, in a dry lake bed in Nevada at 39.739717, –115.388916. And the ones in Nevada have exactly the same trajectory, as those in Montana.
But when you zoom in closer you begin to make out the ejecta splashes of oblique impacts into the sediments of the lake bed . Some of these in Nevada are much bigger than the ones in Southwest Montana. This one’s almost a mile long.
And, on the northeast end of the lake bed, we find the lowest, and youngest, beach lines are lying across an ejecta splash. The beach lines over-lapping the ejecta splashes that way should provide an excellent stratigraphic horizon. That’s where we get our date from.The early Holocene age of those beach lines, and the trajectory of the impacts, imply that these oblique craters were produced sometime around the end of the last ice age. And in exactly the same fall as those in southwest Montana.
That dry lake bed, and others like it, just might be a meteorite hunter’s paradise.