Test Fest

Test fest - thanks, volunteers, for all the digging and notetaking! 

Wanted a better handle of the sensitivity and distribution of the 1/13 crust and weak layers, particularly in anticipation of the warming headed our way at the end of the week. Used a long, east-facing ridge as a transect, and conducted large column tests at 4 northeast to southeast facing sites.

• 1/13 melt-freeze crust down 80 to 105 cm. It was knife hard in the 3 pits below 6000 ft, but only pencil hard at 6200 feet - noticeably softer, though it doesn't sound like a big difference.
• In the 3 pits on the shaded side of the ridge, preserved surface hoar was present 2-7 cm above the 1/13 crust. The stripe grew more visible with elevation.
• In 2 (4850 feet and 6200 feet) of these 3 profiles, extended Column Tests propagated with hard force. In these same 2 profiles, Propagation Saw Tests produced cracks that ran to the ends of the columns. The most dramatic results in both tests were at the highest site. 
• At the southeast-facing site (5000 feet), large column tests produced no failure on a thin layer of facets above the 1/13 crust, and a PST did not result in a score indicative of propagation propensity. 

Takeaways? It's getting harder for a person or snowmachine to collapse the surface hoar as it's buried deeper and degrades. Find a shallow spot where the layer's well-preserved, however, and it can fail spectacularly. This doomsday scenario seems more likely above 6000 feet, where the surface hoar layer is more distinct. After today's results, alarm bells would go off if I saw another profile where there's still an obvious, 1 cm-thick layer of surface hoar near the crust. Obvious as in visible from outside the pit.

Eggshell crust now on the surface after a brief freezing rain event early afternoon. Some impressive cornices and drifts on the ridge above 5700 feet, though we didn't detour from our test-fest to see if they were fragile. 

Images and video to come.