2 January 2015
Devonian metamorphic rocks (garnet-bearing gneiss) exposed on the western side of Cabbage Island, Maine:
And here it is in GigaPan form:
1 January 2015
A list of birds seen in my yard this year.
- Downy woodpecker
- Mourning dove
- Dark-eyed junco
- Tufted titmouse
- White-breasted nuthatch
- Black-capped chickadee
- Pileated woodpecker
- Red-bellied woodpecker
- Turkey vulture
- Hairy woodpecker
- Eastern phoebe
- Red-tailed hawk
- American crow
- American robin
- Bald eagle
- Brown creeper
- Barred owl
- Carolina wren
- Brown-headed cowbird
- Chipping sparrow
- Broad-winged hawk
- Black vulture
- Blue-gray gnatcatcher
- Ruby-throated hummingbird
- Yellow-throated vireo
- Sharp-shinned hawk
- Rose-breasted grosbeak
- Blue jay
- Indigo bunting
- Red-eyed vireo
- Barn swallow
- Baltimore oriole
- Yellow-rumped warbler
- Yellow warbler
- Hermit thrush
- Great crested flycatcher
- Scarlet tanager
- Common nighthawk
- Great blue heron
- Eastern wood-peewee
- Yellow-billed cuckoo
- Cedar waxwing
- Chimney swift
- Eastern bluebird
- Red-shouldered hawk
- Black and white warbler
- Yellow-bellied sapsucker
- Black-throated blue warbler
- Purple finch
- European starling
- Red-winged blackbird
Again, the total species count went up. This pleases me. It means I’m probably spending more time outside and learning to identify new birds.
31 December 2014
I love moraines, rocky beaches, gravel bars – they are like a giant smorgasbord of delicious goodies. Here, for instance, are some close-ups of a trilobite-bearing boulder on the south lateral moraine of the Athasbasca Glacier, Jasper National Park, Alberta.
And what are these things? Any ideas?
30 December 2014
Some boulders seen on the trail to Helen Lake sported lovely sets of Skolithos trace fossils. Here are two boulders, with the perspective on the tubular paleo-vertical Skolithos burrows being “map view”:
Another boulder, in the middle of the trail, showed them in a fine cross-sectional view:
It also included some interesting “ribbed” vertical traces that I didn’t recognize as familiar:
…Diplocraterion, perhaps? Seems too “linear” and not curved enough for that, though. They are about 3 or 4 times as thick as a “typical” Skolithos, which I would say is 3-4 mm.
29 December 2014
Look at this! A whole boulder made of trace fossils. Three photos, each more progressively zoomed in than the last.
Update: The @ichnologist identifies these as perhaps Thalassinoides.
26 December 2014
That pretty much speaks for itself, I reckon.
25 December 2014
Posted this morning as my “Christmas gift” to blog readers in both photo and GigaPan form, here are the exquisite stromatolites of Helen Lake, Banff National Park, Alberta.
Finally, three other non-stromatolitic GigaPans from the site:
One of Artomys Formation siltstone / shale interbeds…
…and two of Cirque Peak itself, showing its gorgeous internal folding:
Happy holidays to you!
The long hike to Helen Lake (Banff National Park, Alberta) is worth it, not only for the mass wasting and glacial geomorphology, but also for the stromatolites.
Just another day in the office…
As a “Christmas gift,” enjoy these images… some of the loveliest stromatolites I’ve ever seen:
24 December 2014
This is Helen Lake.
It’s a lovely little tarn. I hiked there last summer with Aaron Barth, to do some GigaPanning of stromatolites. But we’ll save those images for another day. Right now, I want to focus on the geomorphology of this valley.
A wider view of Helen Lake’s setting can be seen in this GigaPan:
One thing that I hope will catch your eye in that GigaPan is the big pink googly eye on the cliffs at left (south) in the background. This is a rock fall deposit:
Here’s a GigaPan of the rock fall:
The rockfall shows up so well because fresh Gog quartzite is very light in color: white or pink. But when it’s been exposed for a while, it tends to host lichens, and they come in green and gray varieties, as seen here:
Super; So that’s straightforward and understandable. We can see the source area of the slide on the cliffs above. We can see a little nubbin of the darker underlying sedimentary rock poking through in the middle. Case closed. But what’s this thing in the middle distance??
Wait, Callan. What “thing” are you talking about?
At first glance, you might be tempted to classify this as a lateral moraine, since it’s a linear feature along the side of the valley, made out of bouldery sediment. However, compare it to this example of a lateral moraine, from the Athabasca Glacier:
You can see that till, the poorly sorted sediment that makes up a true lateral moraine, is dominated by lots of finer-grained stuff in addition to the big boulders. The big guys “float” in a finer-grained matrix. With the Helen Lake example, however, it all seems to be big stuff – the character of the sediment looks distinct from the till I would expect a moraine to be constructed from. It looks more like a talus slope, made of bouldery colluvium, except that it’s clearly offset from the base of the cliffs. Maddenigly, like a lateral moraine, it follows the valley upslope…
I’m tempted to call this a protalus rampart. If I understand the term correctly, it implies partial glacier melt-back, followed by an extended period of time when snow and ice remain in the deepest “corner” of the valley. Spalling of rock from the cliffs above triggers rock fall, but the resultant boulders land on the snowy slope, sliding like blocky sleds downhill to pile up at the toe of the snow slope. Later, the snow and ice melt away, removing the “ramp,” and isolating the line of talus from the source cliffs. What do you think? Have I got that right?
…Or is something else going on here?
23 December 2014
Two years ago, I posted on some interesting structures my students and I saw at Consolation Lakes, near Moraine Lake in Banff National Park. They were little concretions, “oncoids” roughly speaking, and may have indicated (thanks Howard!) that the boulders were sourced to the Peyto Formation, a Cambrian carbonate within the Gog group:
The purpose of today’s post is to confirm that these structures are still there two years later, and to post a few more photos of them:
Note the negative weathering the oncoids show relative to the surrounding matrix.
I also found a couple of boulders at a new location, in the lateral moraine of the Athabasca Glacier that had the same features, though less oxidized…
Note the ooids (upper right) and radial cracks in the “oncoid” here: