A cold rain on Monday was freezing on the trees, so we explored some of the many undeveloped road networks in Fairfield Bay, especially along Dave Creek and down to the lake on the east side of the map.
Not quite sure what we’re in here, but there is a calcareous sandstone massive not too far above lake level which could indicate that we’re still in the Witts Springs even though this is south of the lineation along the Middle Fork. We’re getting a lot of strong southerly dips along the north edge of the lake which indicate there is a fault along that lineation, unfortunately the lake covers it. Too bad this detailed geologic mapping was not done prior to 1963!
Tuesday we finished up the upper end of Big Branch. The ice was still on the branches when we started, but soon began to melt which made it seem like it was raining again until about noon.
At first, we thought we were finding additional Witts Springs/Cane Hill contacts, which was surprising since we were so far above where we had them downstream last week. But we definitely had a thin-bedded sandstone that was shaly near the top beneath a classic basal Witts Springs sandstone.
Or did we? As it turned out, the thin-bedded sandstone was only about 40-60 feet thick and was above at least two other massive sandstone units. Another Cane Hill look-alike! That’s why you always have to look at the entire section, or you may miss something!
What we took for the basal sandstone massive may actually have been the uppermost sandstone massive in the Witts Springs. As we hiked on downstream, we did eventually find the actual Witts Springs/Cane Hill contact that lined up much better with the points we already had.
Wednesday, it was so cold the moisture being wicked up certain grasses was making “frost flowers”.
We walked up the lower end of Little Creek along the western edge of the map. We had already seen the upper portion when we mapped Old Lexington, and it seems to be all Witts Springs in there. We saw some good examples of “zebra rock” and “Prairie Grove weathering” in some of the massive sandstone units (see previous blog).
Some of the calcareous sandstone is also fossiliferous, and I was lucky enough to find a good rugose coral weathering out in one fossiliferous zone.
Well, looks like winter is here to stay! At least I don’t have to watch for snakes anymore! Until next week, see you on the outcrop!