Thanks for your comments guys.
FishinRod,
Our frost line appears to be very shallow. I've never found frozen soil deeper than 6". Authorities consider it to be a couple of feet however. We have few days in winter that stay below freezing all day. We don't have continuous snow cover, but when the air temps are below 32 for a period, there is generally a blanket of snow.
Our horticultural irises do very well.
I did plant the yellow water irises on the north bank of the pond. Almost all of our shoreline drops straight down about a foot at the full pool point. The bank seems to be stabilized by the intertwined roots of a thick growing fine stemmed rush, or cattails and bulrushes. I've tried to get three cornered bulrush established without success. Rather than plant on that vertical bank, perhaps I need to try planting on the pond bottom itself? That would be in about 1 foot of water at full pool. As our climate is very nearly desert, I may have to water plantings in the late winter and early spring when the exposed pond bottom is at its driest?
We do have two Mancos shale outcroppings. Fossils we've found include only shells, no shark teeth yet. A neighbor several hundred yards away has big ammonites on his place, 20" in diameter or greater.
jpsdad, we see extensive patches of those lovely wild irises in some large meadows at somewhat higher elevation, and the plants are abundant up in our Ponderosa pine woods in many swales. I've transplanted some which have dwindled and disappeared over the years. I'll have to try again, placing them in spots I can water in winter and spring.
