Today's efforts in terms of geology were twofold. First, we took the ATV's out today out of sim to reconnoiter the routes to Lith Canyon and to Candor Chasma Canyon, referred to as a "must see" by a previous rotation. Part of the reason we made these recons was to prepare for a visit of media folks next week, but part was just to scope out the areas for further geological investigation. If anyone from previous crews who have visited Lith Canyon could reply to me at the Hab within the next day or two, I would be happy to hear more about the canyon. The waypoint database makes numerous references to the rocks of this area, but I'm still not perfectly clear whether the name Lith Canyon refers to the very large (>.75 km wide?), open, barren canyon in the Morrison centered about UTM 12 E0518500 N4256500 or to some small slot-like canyon within this large feature. So if you have information that would be helpful, do let me know.

While on the south side of this large canyon, we saw some beautifully petrified wood. Fragments trailing down slopes caught our eye, and we worked upslope to find the source. There was an abundance of fragments nearly in situ, some firmly adhering to a fine conglomerate, if I may use the term, a rock unit below the Dakota Sandstone, separated from it by perhaps 100 feet of section, or a bit more. This unit is, I think, the same or equivalent to that upon which the observatory sits.

I'm still interested in the sandstone which supports the observatory. In some places it seems conglomeritic, in others not. It is often cross-bedded and usually yellow, but especially farther north of here, near the end of Cow Dung Road, it seems to be not cross-bedded and white. It is typically not very think, perhaps on the order of 20 feet/6 meters. It forms the caps of low hills on the Hab level, and it is seen in most places, cropping out below some particularly red shales just below the Dakota. At least these are our observations so far.

To look at this unit a bit more closely, we performed an EVA this evening walking from the Hab. We headed south, along the base of Hab ridge, tracing as well as we could the Observatory Hill sandstone. We also took several strike and dip readings on various bedding planes on resistant strata. These beds were striking a few degrees west of north (unadjusted magnetic), with dip to the west at a low angle, perhaps less than 5 degrees.

(I want to state, however, that it was quite difficult to take these readings with a Brunton compass while in full sim -- not so much from the handling of the compass, but because it was quite hard to see the dip level, both because of reduced visibility through the helmet and because it was hard to get my head low enough to be in a position to see.) I'm interested in comparing these values to regional strikes and dips from other sources.

We then turned and passed the Hab heading north, again looking for outcrops of this layer on the low hills between the Hab and the butte visible from the kitchen window. We found good outcrops, and this layer appears to be entirely a fine conglomerate on these hills.

Despite the gentle dips and the ease with which one can typically trace strata by eye in these hills, some uncertainty remains because of the abundant red and white layers. Specifically, some of the outcrops of the Musk Observatory Hill sandstone/conglomerate just north of the Hab seem out of place, lower in the section than one would expect. This is probably simply due to our imperfect understanding of these relationships, but I've also wondered if a large slump off of Hab Ridge might have displaced this unit down in the section. I do not think this is the most likely explanation. Indeed, I think the more likely explanation is that we just haven't correlated the strata perfectly, but I'd be interested in any feedback from some folks who have been here before or from anyone else.