Cob: New Deck Steps (earthbags)

[Chrys Mollett]

Hi all you cobbers & soon-to-be cobbers.
Chrysara here from Murphys, CA (Mother Lode, sierra foothills) and I believe
this may be my first foray into
the Coblist. I DO appreciate this forum for questions and experience & ideas
for cobbing and green building folk.
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It's interesting to me that SO many messages include the words:  "I'm
planning to....."
Well, me too, I'm planning to, too. I have made a model-test cob material
thing shaped like looking down into the top of a bell pepper. Put it on a 1
x 2' roofing brick recycled from the local hich school which burned down
(nothing left but these lichened bricks!)
I've promised I'd begin some cob project this spring (finally), and I needed
a safe step-up & down from my deck, so I filled some 12  feed grain bags 2/3
full with earth (no stones) and hauled them up the hill from an old burnpile
(a la N. Khalili) They've made a wonderful and graceful step area now.
Still sort of nice & cushy underfoot.
BUT I'm needing help with what to use to cover them to protect the bags from
deteriorating in the sun (intense sun & heat hitting the west end of deck -
also mild but pronounced winters here). I'm hoping to avoid the high
production-waste concrete route and hope that won't be necessary; SO,  what
do I add to the cob to protect the bags?    I have a little time, but not
long before the real hot days will begin here. What say you or you or you?
Thanks ahead.  Chrysara M. from Murphys harpland at caltel.com