[capitan_refugio]

I have worked in tuff deposits before, in the area around Bishop, Mono Lake, and Mammoth, CA. The problem with tuffs is that a "single event" in the geologic record might actually have happened over several months or even years. Take the case of a hypothetical ash vent in the Long Valley Caldera (Mammoth area). It might blow ash for a long time, with the deposited ash not showing much of any "bedding," grading, or flow lamination.

These types of deposits are best dated by the material immediately above and below the deposit in question - so you get a range.

[Mike Darancette]

Take the case of a hypothetical ash vent in the Long Valley Caldera (Mammoth area).

The Bishop Tuff and around Mono Lake is less than 50 miles from the Long Valley Caldera so that smaller ash vents could have contributed to the deposits over time ie Inyo and Mono Craters. It would take a pretty large blast to expel tuff thousands of miles and those don't happen too often from one caldera.

I would be interested in knowing if and where they have found any welding in these deposits (Asia).

I have been going to the area around Crowley Lake, Mammoth Lakes and Bishop for over 45 years. I am not a Geologist but even as a kid I wondered why the area around Crowley Lake and the Owens River Gorge looked so weird.