What’s it about?
Isotopes of oxygen and hydrogen from water can give us insights into the altitude at which that water fell to the ground as rain. Some of this water can become incorporated into volcanic glass (in ash), preserving the isotopic values of the original water.
Why does it matter?
When we can quantify the altitude of a place, particularly mountains, at ancient times, this makes it possible to understand the processes by which mountains grow. Most of the time, this is done with isotopes of oxygen from carbonate minerals in fossilized soils. It is now possible to do the same research in an area that lacks ancient soils, but has volcanic ash layers instead.
Why did I read this?
I have two reasons. One, I work in a lab where many of the researchers are specifially answering questions about ancient elevation. Two, I am assisting some researchers in doing this exact type of analysis: estimating elevation from volcanic glass.