In the parking area near Bandon's south jetty stands an interpretive sign similar to dozens scattered along Oregon's coast. The only substantial variation between them is the placement of the "You Are Here" flag. As I've mentioned before, one might guess, with the heavy coverage of these signs in low-lying areas near the coast, that some sense and restraint might be shown with respect to development- particularly of housing- in these areas. And, as I've mentioned before, one would be disappointed...
Looking southwest from Bandon's south jetty, you can see the numerous sea stacks that are so characteristic of Oregon's southern coast. The rock unit here is Otter Point Formation, a highly variable and highly faulted melange. The combination of rock variability- from poorly consolidated graywacke and serpentinite to very tough blueschist- and abrupt transitions between them along with fracturing due to faulting results in extremes of differential weathering and erosion. The end product is a grand coastline that is as nice as any I've seen elsewhere.
Looking out along the south jetty of the Coquille River at Bandon, the blueish, schisty texture of the boulders is evident in the foreground. Over on the left, Dana is hunkered down looking at, well, something. There are scads of pretty minerals to find, though many of them I'm unable to identify on sight alone. And to clarify the allusion in the post title, there aren't any monkeys here, let alone twelve of them.
Looking across the mouth of the Coquille River to the north jetty, Dana asked a perfectly logical question: "Is it made of blueschist, too?" I had not considered the question before, and I honestly don't know the answer. Given what I can see at that distance- basically color alone- it looks consistent. And certainly, given the circumstances of construction, I'm guessing both jetties were built together. It wouldn't make sense to only have one for some period of years. Since a quarry close to the water was established to supply the stone blocks for the south jetty, it would make sense that the same quarry was used at the same time to supply stone for the north jetty. So I'd be willing to bet a small amount that the north jetty is blueschist, too, but I'm just guessing with logic. I don't really know. I *do* know that people sometimes visit that light house, so that jetty probably isn't too hard to get at... ROAD TRIP!
I'm really not sure what this pocket of minerals actually is, but lawsonite seems a reasonable guess. It's fairly common at Bandon's blueschist jetty, and should be easy to find for other visitors- probably not this same block, but there are plenty of similar samples. In reading over the wikipedia entry on lawsonite, the thing that jumped out at me- which I had either not known or had forgotten- was how hard that mineral is: 7.5-8 on the Mohs scale. This gives an easy, if not necessarily diagnostic, field test if you have or can find a bit of quartz lying around. A fragment of lawsonite would be able to scratch quartz, and there are relatively few minerals for which that's true. I need to remember that the next time I visit Bandon!
There's a lot going on in this block. First, there's the exquisite weirdness of blueschist, which never really gets old, no matter how much time you spend at Bandon's jetty. Next, it looks as if the rock was cataclastically shattered during metamorphism; the white slabs (quartz?) on the left can be sensibly reassembled into a more or less coherent whole. On the other hand, the clasts around and above the hammer's head look more chaotic. Finally, there are a number of what appear to be veins shooting through in a few places. The two that are clearest are running through the slabs on the left.
Here we see a fairly common phenomenon in sheared coarse metamorphic rocks: a tendency to segregate into separate groups. I don't entirely understand this; it certainly isn't based on something as simple as color, though it can appear to have that effect. It's more likely due to some physical characteristic like susceptibility to plastic deformation. In this case, more plastic mineral groups such as chlorite end up somewhat segregated from less plastic minerals, like the glaucophane. Also, if you enlarge the photo to full-size, you can spot bright little red garnets all over the place, though for me, at least, they tend to stand out better from the lighter micaceous matrix.