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Posts Tagged ‘Sandstone’

On Sunday, the family and I headed towards the Blue Ridge with the intentions of stretching our legs along the Buzzard Rock North trail. According to hikingupward.com this is an easy trail with a few great vistas along the ridge. While they were spot on about the views, the word “easy” is relative and I don’t think it related to us on this excursion. Not that it was difficult, just that it wore out our poor 11 year old pooch who I had to carry at one point.

The trip was simply recreational and I had no plans of making anything geologic about it, though I did bring my rock hammer, hand lens, HCl, and chisel. Even still it is a hard skill to turn off and I noticed a few rocks that caught my attention. It should come as no surprise that Massanutten Mountain is comprised almost solely of the Massanutten sandstone (MSS). The MSS is a quartzite meaning that it is almost all quartz grains, therefore making it very durable. What I find very interesting, and what caught my eye along the hike, is the range in grain sizes of the quartz. I found rocks of well sorted sand sized grains all the way to large pebbles in a conglomeritic rock.

In all cases the larger pebbles of quartz were weathering away at a lesser rate than the smaller sand sized grains, making them pop out and be even more noticeable. In the rock pictured below the larger pebbles were almost ready to be plucked out of the rest of the rock.

Along the hike there were nice examples of cross bedding seen in a lot of the sandstone. Since it may be hard to tell from the picture below I added some nifty red lines to help in the visualization. While this example is not in situ, cross bedding was seen in the MSS to show it was not overturned.

The hike up to the first vista point is pretty straight forward, up and down a few hills, across a stream or two, but after that it gets more interesting. From this point the incline steepens, and your path is more likely to be MSS than the soft soil it was before. Once we reached the top (and took a desired breather) the trek along the ridge was full of great views of the Fort Valley and the other side of the basket. It was also visible that the beds of MSS were dipping towards the valley, some as steeply as 75°. Combined with the cross bedding orienting our paleo-up position this shows how Massanutten Mountain is part of a synclinorium. The entire valley is folded down in a syncline with parasitic folds as part of it, and the MSS is so durable it weathers away at a slower rate than the surrounding shale.  Much like the quartz pebbles in the conglomerate, Massanutten Mountain sticks out in high relief of the valley.

Along the ridge was where we set ourselves down and enjoyed some turkey sandwiches and fresh strawberries, and I can probably think of a million worse places to have a lunch than here:

We were also privy to some wildlife besides the vicious attack dog we brought with us. Up top we saw one of Virginia’s two vultures, the black vulture, which is distinguishable by the white tips to its otherwise black wings. And along the lower half of the trail we saw this little guy who I think is a gypsy moth, though I am admittedly not great at identifying my caterpillars.

The trip down was swifter and a little easier on the legs, though we were all pretty tired at this point. None more so than the dog who eventually just stopped walking and decided she had had enough. So let me ask you, who is the subservient one in this relationship then?

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