Excavating around volcanoes can be beneficial as doing so can give a good temporal marker. Generally in Alaska when we dig, we pop the root mat off and scrape the bottom of what is stuck to the tundra. So here, I’ve just popped off the top of my unit making the stratigraphy upside down with the bottom of the exposed sediment being the top of the root map.
Regardless, the nice, thick gray to brown layer is completely volcanic ash. Many areas in Alaska still aren’t studied well enough to know which ash is from what, but due to its thickness, this ash layer is likely from the largest known historical eruption of Augustine in 1883, or the 1912 Katmai eruption.