By Dave Tucker, with new material provided by John Scurlock and Steph Abegg.
Here is an update on the May 31, 2013 debris flow in the Middle Fork Nooksack valley.
Video of the deposit in the river channel is on YouTube.
Thursday afternoon an aerial reconnaissance of the Deming Glacier and upper Middle Fork Nooksack valley was made by photographers John Scurlock and Steph Abegg. Their photos show a large landslide scar on the side of the Little Ice Age lateral moraine above the toe of the Deming Glacier.
The Deming Glacier appears intact and does not show evidence that it contributed water in any substantial way to the debris flow. The moraine consists of inherently unstable, unconsolidated glacial sediment, ranging from sub-millimeter clay to huge boulders. At this time of year, it is likely that the sediment was saturated. Additional water may have come from melting snow banks above- see the first photo. Photos show that the landslide began around 4600′ ASL at the top of the moraine where it is inset against volcanic rocks erupted from the Black Buttes volcano. It slid about 400 feet down onto the very terminus of the
glacier, and ran up the opposite valley side a short distance. The water-saturated sediment then gained additional water from the river, and roared down the valley. The high-mud mark is plainly visible well above the valley bottom in John’ s photos.