Sitka Nature

Graupel is a type of snow that forms when snow flakes fall through parts of the atmosphere that have supercooled water droplets. Instead of maintaining the form of flat snow flakes and/or elongated snow crystals, the supercooled water condenses as a rime on the surface that results in a pellet shape. Superficially, graupel looks a bit like hail, and many people call it that, but hail is a solid ball of ice that forms in repeated freezing/thawing cycles as water/ice is subject to updrafts and downdrafts in thunderstorms. With a little extra attention, it’s not hard to identify graupel from its less solid feel and slightly fuzzy appearance.

In Sitka, graupel is a fairly common form of precipitation from at least late fall through spring. I remember as a kid noticing that it seemed to fall, sometimes quite heavily, and then shortly after, a more traditional snow would begin. At this point, I’m not sure how strong that relationship is, but it did hold this week. We had a fair amount of graupel Saturday, especially in the afternoon and evening, with snow developing later in the evening and falling through much of the night. Perhaps the conditions that prevail as a front moves through are conducive to graupel formation, with snow falling after the passage of the front.

I could have included this my previous post on the Katlian Outcrops, but I thought it deserved it’s own post for a couple of reasons. First, it will make it easier to find in the future, and second I hope it helps me remember the lesson I should have learned many times before.

The outcrop was basically a cliff that seemed to go well below the bay’s surface. It was a good thing it was high tide, or I probably would not have been able to get off and look around at all. During the course of my visit, I walked a short distance along a ledge that varied from a couple of feet to several feet wide, bare rock in some places with a fair amount of vegetation growing in others.

In the first spot of vegetation I came to, I noticed a handful of empty limpet shells scattered over a small area on a carpet of moss protected by the trees and shrubs growing there. A few feet away, I noticed another shell on top of a very small ledge a foot or two off the main ledge I was standing on. I had a bit of curiosity about the shells, but was mainly focused on looking for different-seeming plants, so I only paused briefly to consider the shells and did not take any pictures.

I continued walking down the ledge a little bit further before turning around. At one point I noticed a small dark brown bird fly along the base of the cliff below me, but I had not noticed any other obvious (to me) bird sign on the ledge.. I looked at the shells as I neared my pick up spot, but by this time I had my hands full with rock fragments and bryophyte collections, so it did not seem worth it to take the time to put it all down and take a picture of the shells and their context.

Of course it wasn’t long after leaving the cliffs and heading back into town that the limpet shell mystery started to dominate my thinking about the place. I was kicking myself for not taking some pictures, it would have only taken a minute or so, and I knew this was a location I would not be likely to get back to soon. It’s not that the photos would necessarily have helped me solve the mystery, but they would have made it easier to verify my memories of some of the details and check for things I might not have noticed at that time. Plus it would have been nice to illustrate this blog post (which is one of only a few that don’t have photo illustrations) to give others a better chance to offer suggestions as to what the shells may have been saying.

If anyone has thoughts/ideas about the shells and how they came to rest where they were, I would be interested in hearing them. I will share my own theories in a follow-up post.

Rock Outcrop in Katlian Bay

Last summer while hiking on Starrigavan Ridge, I noticed some interesting looking rock outcrops along the shoreline of Katlian Bay. They appeared to be more red in color, and after my experiences at Red Bluff Bay, I wondered if maybe it was an outcrop of similar rock.

It was only a couple of weeks ago I was able to get a ride into the bay to get off on shore and take a quick look. It was definitely a different rock type than the greywacke that seems to be the most abundant rock type close to Sitka. It had a different texture, some surfaces showing a bit o gloss, but others very rough from repeated fracturing. It seemed to fracture very easily, and more freshly exposed rock tended towards dark and/or greenish colors while exposed rock tended more towards brown/reddish colors. I have a very limited understanding of geology, but I associate the name serpentine with what I was seeing (though I suspect that is incorrect).

There was not much in the way of new plant growth, but I took a quick look around to see if there was evidence of anything particularly different looking. It was a somewhat different assemblage of plant species than I usually think of for protected shoreline rocky/cliffy areas. Overall there was nothing that immediately stood out as especially unusual, though I thought seeing Shore Pine (Pinus contorta) away from muskeg-like habitats was interesting. (Despite the common name, Shore Pine is not so common on the shores around here, I have seen it at least one other location – though the shoreline of Kamenoi Point Beach is quite different with volcanic sand predominating and extensive muskegs not far upslope).

It would be nice to get back there in early summer to explore more extensively after the herbaceous plants have had a chance to grow out. There are also another couple of cliffs that are nearby and at least as large as this one, which might be interesting to check out as well.

After nearly two months that seemed unseasonably warm and lacking in precipitation, this week has been a return to what I tend to expect of late winter and early spring weather. Monday’s cooler temperatures with heavy clouds and rain, were followed by a short reprieve in partly-cloudy Tuesday, but Wednesday temperatures dropped again, and we saw rain, snow, sleet, and maybe even a bit of hail broken up by brief patches of blue sky an attending sun.