former shorelines, Lake Agassiz, North Dakota.
former shorelines, Lake Agassiz, North Dakota.
I wonder what made the old shorelines so straight and right-angled?
"Kirchner was startled when the nuclide concentrations in the sediments he drew out of streams in 37 different catchments in Idaho's mountains revealed erosion rates over the past 5000 to 2700 years that averaged a whopping 17 times higher than modern-day rates, a finding he reported in the July 2002 Geology. After ruling out climate change and other factors, Kirchner concluded that the huge discrepancy must be due to catastrophic erosion events so rare that decades of regular observations are unlikely to spot them... One lesson to be drawn from this study, Kirchner suggests, is that in young, dynamic mountain ranges, engineers may be greatly overestimating the time it will take reservoirs to fill with debris should one of these catastrophic events occur in the reservoirs' lifetime." -- "Subtleties of Sand Reveal How Mountains Crumble" [related to cosmogenic nuclide dating](I was actually browsing for files on the Channeled Scablands flood event, but this one caught my eye)