Today was a great day for geology. The front that blew through yesterday afternoon and evening brought clear skies today and almost unlimited visibility. We had a fairly lengthy EVA planned for today to the Lith Canyon area, with 2 goals: the first was to explore down the canyon to see if we could find samples of the white sandstone that we have been finding on recent EVAs at about the 4400 foot elevation; the second was to provide a film crew from Discovery Channel Canada with a good chance to film us in action. Also, as always, we wanted to keep our eyes open for interesting specimens which might have collected in the canyon bottom.

Our trip north along the Lowell Highway was uneventful, but we were again struck with the beauty of the red and grey clays of the Morrison in the badlands just a few kilometers north. We passed a couple of exposures of the Dakota Sandstone at about 519500 E and 4256000 N and turned left, continuing on ATV approximately 500 meters, generally heading northwest. We were able to continue on foot into the canyon, and we worked mostly down the drainage.

Once in this drainage, we encountered beautiful white sandstone right off, and we took smaples. It was slightly cross-bedded and medium grained, and comparison of it back in the Hab with the samples from the other locations (White Rock Canyon, Muddy Creek, and the north end of the Lowell highway) shows it to be the same. We achieved our primary goal very early, which allowed us the freedom to simply walk down the canyon with open eyes. Although we couldn't go far, due to pour-overs formed in the sandstone with drops of 5 or more feet, we did make an interesting discovery.

Low in the wash on the east side of the canyon, at a location 518640 E and 4256439 N, we found an outcrop of the same sandstone about 5 feet high and 12 feet long. This outcrop had beautiful slickensides on it, nearly vertical. I spent some time discussing with the other members of the EVA team the method of formation of slickensides and what they tell us -- that motion has occurred along a joint/fault, causing the scratches or pattern to occur on the rock surfaces. Although I have no reason to believe that this surface represents a significant displacement, still this is evidence that motion has occured. Although I have read in one previous geology report that a minor fault was located south of the Hab in the Dakota sandstone, noted, I believe, because of displacement, I have read no references to slickensides and no other references to any faulting, although there may well be some comment somewhere. We do not know the vertical extent of this fault surface, its throw, nor its age, but we have taken the first step by locating it. So here we are, able to add our bit to the information about this area.

The slickensides and the surface they are developed on are nearly vertical, as I noted before, and the strike of this fault surface is more or less northerly. (I did not have my Brunton today to take a strike and dip reading.) Not coincidently, I think, the canyon trends in the same direction. It would be great to return there and seek out other fracture surfaces in this sandstone unit, trying to see if there is any aspect of joint control in this canyon system. I think this would be an interesting project for further work, for me if I return or for another crew.

A final note about this joint/fault surface is that there is a white, micro-crystalline material on this surface, a few mm thick, with the slickensides developed in it. A drop of acid showed this to be calcite, which was neat to see in the field. This led us to wonder what the source was for this calcite, and (coincidentally or not) we discovered lots of small, highly weathered limestone clasts, dark grey/brown and very angular, in the wash just up-slope. Although we began to search up-slope on the walls of this canyon (clays of varying color at this point) we never found the layer that was the source for the limestone float. Wind and clouds blowing in caused us to cut our explorations a bit short, not wanting to be in a canyon with a chance of rain.

As we climbed up and out on the east side of this canyon, we turned around and looked west, drinking in the view. The whole scope of the geology of this region stretched out before us. In the far distance was a high plateau, snow covered. In the near distance rose Factory Butte, capped by the Emery Sandstone with the Upper Blue Hills of the Mancos Shale below it. Next spread out the Skyline Rim, stretching far from north to south, upheld by the Ferron Sandstone, with an apron of dark blue/grey slopes below it. In the near distance rose buttes capped by the Dakota Sandstone, yellow and brown, the bottom of the Cretaceous. Below this were bright red and grey slopes, with thin sandstone layers, the upper Morrison Formation, our constant companion and friend for these two weeks. And finally, below us on the floor of the canyon, the clean white sandstone of the Salt Wash. White sandstone forms the bottom of this sequence and white snow the top; below the sandstone lies the Summerville, a region waiting to be visited and investigated, and above the snow lies another.