Wednesday, February 06, 2013

Cama Beach

 Cama Beach appeared on these pages frequently last year and probably will again this year.  These are from a brief foray in mid-January following some more landsliding.  Not only has the big gully been active, but a couple of new slides have occurred as well.

The big slide we posted about last year (search on the label 'camano') was quiet all summer and early fall, but has gotten more active this winter.  Water was flowing over the top during this visit and was eroding the sandy unit below the till.  This appears to undercut the till which then fails in larger blocks, although nothing too dramatic has happened yet this year.  Most of the colluvium in the gully still looked like the trodden and rained-on remains of last year's debris.  I would expect more failures as long as the water is flowing, but I wouldn't pretend to guess how large.

One reason for my visit was reports of a new slide south of the one I just described.  Sure enough, there had been a fairly large debris avalanche on the lower half of the slope, in line with a substantial gully that probably corresponds to an earlier slide.  Water was flowing from somewhere mid-slope. This new slide is immediately north of one that occurred in the late 1990s. There is plenty of tree debris on the beach, and a fair amount of dirt, but nothing like the other slide.  There's a steep bare headwall at the very top of the slope, but the upper slope doesn't appear to have failed in this event.  I suppose the recent slide could make that more likely, at least if conditions stay wet.

There was also a small slide - a small earthflow more precisely - on the slope nearer the resort, above where the old bungalows were.  When the park was redeveloped, a decision was made to remove several of the old bungalows at the north end, at least in part due to their vulnerability to slides. Probably a very good idea.


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