Avalanche: Claytons

Observer Name
Mark Staples
Observation Date
Friday, March 16, 2018
Avalanche Date
Friday, March 16, 2018
Region
Salt Lake » Big Cottonwood Canyon » Claytons
Location Name or Route
Clayton Pk Rock Garden Basin
Elevation
10,000'
Aspect
North
Slope Angle
38°
Trigger
Snowmobiler
Trigger: additional info
Unintentionally Triggered
Avalanche Type
Hard Slab
Avalanche Problem
Persistent Weak Layer
Weak Layer
Facets
Depth
2.5'
Width
40'
Vertical
100'
Comments

This small pocket slid when my partner climbed up this slope just right of the rocks. What was interesting is that the stauchwall (bottom edge of the slab that released) was even with the bottom edge of the rocks. Below the rocks the snowpack is deeper but also the slope angle quickly lessens.

This slide released on a layer of facets about 3-4 inches beneath an obvious layer of dust. The dust is not a factor but just a good marker and a good way to find the location of these facets. See stripe of dust in the third photo below.

Locals who've been riding in this zone all winter have been avoiding similar terrain on bigger slopes. This slide is demonstrates the wisdom of that choice. Bigger north facing terrain near rock bands will likely produce bigger avalanches. Rocky areas tend to have weaker and more faceted snow. They also have lots of good trigger points.

Comments

The buried rock in the pit wall in the photo below is a great example of a good trigger point on a slope.

Earlier in the day, we dug just under Clayton Peak first, found the dust layer, but nothing would break in my tests (ECT). This was an exposed windy location. Perhaps the faceted layer had been stripped off the snow surface before it was buried. Moved to the Rock Garden basin just east of Clayton and just north of Caribou. Dug the pit in the photo below. I purposely performed my ECT's above the rock in the pit wall to simulate being in a shallower rocky area. The ECT broke and propagated after 23 taps (ECTP23).

About 15 minutes after doing this test. My partner shot up the small slope and got this avalanche to break out. It was good confirmation of this avalanche problem and of the validity of my ECT next to the buried rock.

Video
Video
Coordinates