2 January 2015

Friday folds: Cabbage Island, Maine

Devonian metamorphic rocks (garnet-bearing gneiss) exposed on the western side of Cabbage Island, Maine:

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And here it is in GigaPan form:

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1 January 2015

2014 Yard List

A list of birds seen in my yard this year.

Lists for 2013 (52 species) and 2012 (32 species) here.

  1. Downy woodpecker
  2. Mourning dove
  3. Dark-eyed junco
  4. Tufted titmouse
  5. White-breasted nuthatch
  6. Black-capped chickadee
  7. Goldfinch
  8. Pileated woodpecker
  9. Red-bellied woodpecker
  10. Turkey vulture
  11. Hairy woodpecker
  12. Eastern phoebe
  13. Red-tailed hawk
  14. American crow
  15. American robin
  16. Cardinal
  17. Bald eagle
  18. Brown creeper
  19. Barred owl
  20. Carolina wren
  21. Brown-headed cowbird
  22. Chipping sparrow
  23. Whippoorwill
  24. Turkey
  25. Broad-winged hawk
  26. Black vulture
  27. Blue-gray gnatcatcher
  28. Ruby-throated hummingbird
  29. Yellow-throated vireo
  30. Sharp-shinned hawk
  31. Rose-breasted grosbeak
  32. Blue jay
  33. Indigo bunting
  34. Raven
  35. Red-eyed vireo
  36. Barn swallow
  37. Baltimore oriole
  38. Yellow-rumped warbler
  39. Yellow warbler
  40. Ovenbird
  41. Hermit thrush
  42. Great crested flycatcher
  43. Scarlet tanager
  44. Common nighthawk
  45. Great blue heron
  46. Eastern wood-peewee
  47. Yellow-billed cuckoo
  48. Cedar waxwing
  49. Chimney swift
  50. Flicker
  51. Eastern bluebird
  52. Red-shouldered hawk
  53. Black and white warbler
  54. Yellow-bellied sapsucker
  55. Black-throated blue warbler
  56. Purple finch
  57. European starling
  58. 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.

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31 December 2014

Tril-o-bits-and-pieces in a boulder on the Athabasca Glacier moraine

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.

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And what are these things? Any ideas?

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30 December 2014

Skolithos in Gog quartzite, on the trail to Helen Lake

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”:

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Another boulder, in the middle of the trail, showed them in a fine cross-sectional view:

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It also included some interesting “ribbed” vertical traces that I didn’t recognize as familiar:

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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.

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29 December 2014

Intense bioturbation in limy mudrock on the trail to Helen Lake

Look at this! A whole boulder made of trace fossils. Three photos, each more progressively zoomed in than the last.

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Update: The @ichnologist identifies these as perhaps Thalassinoides.

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26 December 2014

Friday fold: another gem from the Chancellor Slate

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That pretty much speaks for itself, I reckon.

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25 December 2014

The stromatolites of Helen Lake 2: GigaPans

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.

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Finally, three other non-stromatolitic GigaPans from the site:

One of Artomys Formation siltstone / shale interbeds…
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…and two of Cirque Peak itself, showing its gorgeous internal folding:
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Happy holidays to you!

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The stromatolites of Helen Lake 1: photos

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.

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Aaron Barth and I hike up there last summer to GigaPan them (GigaPan images in a separate post, here).

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Just another day in the office…

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As a “Christmas gift,” enjoy these images… some of the loveliest stromatolites I’ve ever seen:

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24 December 2014

A rock slide and a protalus rampart (?) on the trail to Helen Lake

This is Helen Lake.

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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:

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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:

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Here’s a GigaPan of the rock fall:

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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:

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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??

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Wait, Callan. What “thing” are you talking about?

This one:

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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:

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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…

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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?

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…Or is something else going on here?

 

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23 December 2014

More oncoids (from the Peyto Formation?)

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:

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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:

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Note the negative weathering the oncoids show relative to the surrounding matrix.

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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…

Boulder #1:

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Boulder #2:

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Note the ooids (upper right) and radial cracks in the “oncoid” here:

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