Ice in the Nile Landslide?
October 14, 2009
One of the odd things that we discovered during our investigation on Sunday was chunks of ice in the Nile Landslide. Ice. I guess I should qualify this a bit better. The ice is between the coarse rocks and it doesn’t look much like ice when you are next to it. Here is what I mean:
To get it out of the way, the ice probably didn’t play much, if any role in the landslide failure. It is probably a product of the talus, which in Eastern Washington can sometimes form ice cores. These are well known to many in Eastern Washington and even were mined early on as natural cold storage. This isn’t something I know a whole lot about, but my geologist friend Jack from Eastern Washington explained it to me. Cold air from the surface is able to permeate into the talus, forming a barrier from the hot air. As water infiltrates down into the talus, either through precipitation, snow melt, or shallow groundwater (or other ways), the water hits that cold air and starts to freeze (as long as the air is colder than freezing). The cycle continues as cold air can continue to permeate down, keeping the ground cool and protecting it from the hot air above.
I will be heading into the field on Thursday, either with WSDOT on a helicopter flight or by vehicle. Either way I will be hiking on the west side of the Sanford Pasture Landslide, checking for stability. I’ll keep you posted.