Category Archives: Field Trips

Kicking Wax and Taking Frames

Cross-country ski tracks along the shore of a lake.
Cross-country ski tracks along the shore of a lake.

Yesterday, a big snowstorm dumped about 30 cm (12″) of snow on Minneapolis, and high winds blew that snow around. On my way home from lab, the train worked well, but I definitely chose correctly when I decided to walk home from the train (2-3 km) rather than take the bus. The roads were a mess, but walking wasn’t too bad.

When that much snow falls that quickly, skiing can be much better for getting around than driving. After dinner I hopped on the skis to go tour around the neighborhood and enjoy being on snow for the first time this winter. I’d barely skied half a block when a car got stuck turning and I helped get them through the intersection.

Skiing around the lake was wonderful. There’s something magical about the quiet of lots of new-fallen snow, and even though the skiing was slow-going, it was fun. However, with it being dark and my being on skis for the first time this winter, I didn’t bring a camera with me.

This morning I went out again and took the camera, because there was a lot of neat stuff to be seen. After helping two more cars get unstuck, I made it to the lake. There were tracks: skis (see photo above), boots, snowshoes, and dogs, plus tire tracks in the roads. High winds had also led to drifting, so there were eolian features as well: mini-dunes, scoops, and even some parabolic or blowout features.

Park bench with snow scoop.
Park bench with snow scoop.

Scoops form when wind has to travel around an object such as a tree, rock, or the legs of a park bench. Because the wind velocity increases on the leading edge of the feature, snow or sand get removed from in front of the obstruction.

Minneapolis on a sunny, snow-covered day.
Minneapolis on a sunny, snow-covered day.

The lake is a great place to look for eolian features, because its flat surface without plants or other obstructions provides a large windy area. Miniature dunes formed, with steep faces to windward, and shallower slopes on the leeward side. In the photo of the lake above, the wind was traveling left-to-right. It also features a pair of cross-country ski tracks!

Blowout feature on the leeward side of a lake.
Blowout feature on the leeward side of a lake.

One of the neat features was this blowout on the south (leeward) side of the lake. Last night it seemed to be a fairly parabolic feature, but today it was clearly a blowout. The grasses slowed the wind and provided a place for snow to accumulate, while the gap between grass tussocks was a high-wind area. Scouring is evident near the gap, but deposition follows not far downwind, and the parabolic shape of the features is visible.

Blowout feature on the leeward side of a lake.
Blowout feature on the leeward side of a lake.

There were a few birds out and about this morning, too! A white-breasted nuthatch was foraging in a tree above me, and several other nuthatches were fluttering around nearby.

White-breasted nuthatch.
White-breasted nuthatch.

It was a fun expedition out skiing, and I was happy to take some pictures along the way. The snowplows were busy while I was out, and several of the streets had been cleared before I got back home, so there were fewer cars to help out of the deep snow.

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Capitol Rock Close-Up

Close-up outcrop photograph of Capitol Rock, viewed from the north-northeast.  Image credit: Bill Mitchell (CC-BY).
Close-up outcrop photograph of Capitol Rock, viewed from the north-northeast. Image credit: Bill Mitchell (CC-BY).

Two years ago, I came tantalizingly close to Capitol Rock, an outcrop in southeastern Montana (45.572189, -104.087964) just a few miles over the border from Camp Crook, SD. Unfortunately, I did not have an opportunity at that time to explore the outcrop from any closer than about a quarter mile, but I did find the Ekalaka Quadrangle 30’x60′ (pdf) geologic map.

Recently, I was out in the area again, and this time made sure to have time to take some pictures and see some of what was to be seen. Let’s start with the quarter-mile view, which is roughly equivalent to what I saw last year.

Wide view of Capitol Rock from the east.  Image credit: Bill Mitchell (CC-BY).
Wide view of Capitol Rock from the east. Image credit: Bill Mitchell (CC-BY).

Capitol Rock has three major parts to it: an easily eroded base, a laminated sandstone middle, and a massive sandstone top. A handy turn-out from the forest service road leads right to the base of the outcrop.

The easily eroded base is made of fine, chalky, white sediment sediment, and it remains in horizontal orientation. In several places, this unit is at least superficially porous. Surprisingly, there are occasional chert clasts in the otherwise fine sediments—I’m not quite sure how those would have been deposited or formed here.

Basal unit of Capitol Rock.  Foot for scale.  Image credit: Bill Mitchell (CC-BY).
Basal unit of Capitol Rock. Foot for scale. Image credit: Bill Mitchell (CC-BY).
Cherty clast in the basal sediments at Capitol Rock.  Foot for scale.  Image credit: Bill Mitchell (CC-BY).
Chert clast embedded in the basal sediments at Capitol Rock. Foot for scale. Image credit: Bill Mitchell (CC-BY).

Above the basal unit is a somewhat more resistant, coarser-grained set of beds. These strata are finely bedded, and have a tendency toward spheroidal weathering. Occasionally interbedded with the spheroidal beds are 1–3 cm thick, well-cemented strata of a white or pink color [discoloration?].

Spheroidal weathering of finely-laminated strata.  Hand for scale.  Image credit: Bill Mitchell (CC-BY).
Spheroidal weathering of finely-laminated strata. Hand for scale. Image credit: Bill Mitchell (CC-BY).
Laminations in the unit displaying spheroidal weathering.  Hand for scale.  Image credit: Bill Mitchell (CC-BY).
Laminations in the unit displaying spheroidal weathering. Hand for scale. Image credit: Bill Mitchell (CC-BY).
Non-spheroidal bed 1–3 cm thick and slightly orange-pink in coloration, within the spheroidal beds at Capitol Rock.  Hand for scale.  Image credit: Bill Mitchell (CC-BY).
Non-spheroidal bed 1–3 cm thick and slightly orange-pink in coloration, within the spheroidal beds at Capitol Rock. Hand for scale. Image credit: Bill Mitchell (CC-BY).

The spheroidally-weathered unit also seems to have one or more channels within it.

Contact between spheroidally-weathered strata (above) and easily-weathered basal unit (below).  Possible channel cut at right.  Outcrop height in image is ~10 m.  Image credit: Bill Mitchell (CC-BY).
Contact between spheroidally-weathered strata (above) and easily-weathered basal unit (below). Possible channel cut at right. Outcrop height in image is ~10 m. Image credit: Bill Mitchell (CC-BY).
Contact between spheroidally-weathered strata (above) and easily-weathered basal unit (below).  Possible channel cut at right has been annotated.  Outcrop height in image is ~10 m.  Image credit: Bill Mitchell (CC-BY).
Contact between spheroidally-weathered strata (above) and easily-weathered basal unit (below). Possible channel cut at right has been annotated. Outcrop height in image is ~10 m. Image credit: Bill Mitchell (CC-BY).

The upper unit at Capitol Rock has more massive sandstone (see wide view above). I didn’t notice many channels in this unit, although I didn’t get very close. A butte just to the north of Capitol Rock provided a good photograph (below).

Massive unit of Capitol Rock, seen in the butte immediately to the north of Capitol Rock.  Cliff is ~30–40 m tall.  Image credit: Bill Mitchell (CC-BY).
Massive unit of Capitol Rock, seen in the butte immediately to the north of Capitol Rock. Cliff is ~30–40 m tall. Image credit: Bill Mitchell (CC-BY).

Although I have those observations, I don’t have much for interpretation of them. The depositional environment seems to be relatively low-energy (give or take the chert clasts), evidenced by the flat strata, fine grain sizes, and relatively few cross-beds. Changes in the rock types would suggest changes in the sediment sources or the depositional environment (or both). There may be post-deposition alteration effects as well, such as cementation of the spheroidally-weathering strata.

View SSE from the butte just north of Capitol Rock.  Truck for scale in pull-out near Capitol Rock.  Image credit: Bill Mitchell (CC-BY).
View SSE from the butte just north of Capitol Rock. Truck for scale in pull-out near Capitol Rock. Image credit: Bill Mitchell (CC-BY).

Capitol Rock is an interesting outcrop, and if you’re in the area, I’d recommend a stop. The rocks are interesting, there are US Forest Service campgrounds nearby, and the view is quite nice. These units can probably be correlated to the Slim Buttes in South Dakota (~45 miles east).

Azorella Peninsula Gigapan

Processing the Azorella Peninsula gigapan.  Image credit: Bill Mitchell (CC-BY).
Processing the Azorella Peninsula gigapan. Image credit: Bill Mitchell (CC-BY).

This is the second in a series of three posts about the gigapan images taken on Heard Island (1: Big Ben, 3: Windy City), with more information about the Azorella Peninsula gigapan.

The Azorella Peninsula is on the northern edge of the main part of Heard Island, east of the Laurens Peninsula. It forms the eastern boundary of Atlas Cove (Laurens Peninsula forms the western boundary; see map below). At the west end of the Azorella Peninsula’s southern margin is the heritage zone around the ANARE campsite, two water-tank shelters, a green “apple” shelter, and the area where our expedition made camp. That many of the camps are all in the same area is no accident: Atlas Cove is probably the best harbor on the island (though still not sheltered from a northerly swell), there is a convenient beach for boat landings, and a small step up of elevation from the lava flows of the Azorella Peninsula provides higher ground than the sometimes-inundated Nullarbor.

Heard Island Map, 1985. Image credit: excerpt from the Division of National Mapping.
Heard Island Map, 1985. Image credit: excerpt from the Division of National Mapping.

Getting a gigapan here was not as straightforward as I had hoped. Although there were plenty of pahoehoe flow tops, cracks where a flow had deflated and collapsed in on itself, and other lava flow features, few of them were of a scale and in a location which enabled them to be nicely gigapanned with the tripod I had. With another 3–5 m of elevation, the gigapan would be spectacular.

As it was, there were some additional features besides the lava flows which I wanted to include. For one, the landscape has significant erosional processes happening, and there are sandy areas which get washed when it rains. Even more than the rain, though, the wind creates eolian features. Many of the small rocks have a little dune in their lee, and often the Kerguelen cabbage and Azorella moss grow on the leeward side of rock barriers as well. Some of this organization is visible in the gigapan.

At the top right of the Gigapan image, and lost to the fog and overexposure of the image, is a strongly layered prominence: Corinth Head. Although I would have liked to go see this outcrop up close, our permit did not allow that—the area is a major nesting site for burrowing seabirds, and in places there are lava tubes with thin ceilings which may give way underfoot.

Corinth Head, Heard Island, viewed from the south (further east than the Gigapan was taken).  Layering is clearly visible, and is likely of igneous origin.  Image credit: Bill Mitchell (CC-BY).
Corinth Head, Heard Island, viewed from the south (further east than the Gigapan was taken). Layering is clearly visible, and is likely of igneous origin. Image credit: Bill Mitchell (CC-BY).

Where the Azorella Peninsula lava flow field meets the Nullarbor, there was a little flow which caught my eye. There, one flow clearly traveled through an older channel or tube. Weathering has removed some of the older flow, giving a cross-sectional view of the dark vesicular rock.

Lava flows of the Azorella Peninsula meet the Nullarbor.  An older, grey unit is visible with a redder unit in the middle.  Notebook is 19 cm wide.  Image credit: Bill Mitchell (CC-BY).
Lava flows of the Azorella Peninsula meet the Nullarbor. An older, grey unit is visible with a redder unit in the middle. Notebook is 19 cm wide. Image credit: Bill Mitchell (CC-BY).

Some lava tubes showed obvious signs of deflation or lava tube collapse. The one seen below had eolian features nearby, and the Kerguelen cabbage and Azorella moss can be seen growing on the leeward side of the rocks. An elephant seal is also present.

Deflated lava flow beside the Nullarbor on the Azorella Peninsula, Heard Island.  Some eolian features are present.  Note the Azorella moss and Kerguelen cabbage at right, in the lee of the solid rocks.  The tan mass at right is an elephant seal.  Notebook is 12x19 cm.  Image credit: Bill Mitchell (CC-BY).
Deflated lava flow beside the Nullarbor on the Azorella Peninsula, Heard Island. Some eolian features are present. Note the Azorella moss and Kerguelen cabbage at right, in the lee of the solid rocks. The tan mass at right is an elephant seal. Notebook is 12×19 cm. Image credit: Bill Mitchell (CC-BY).

Finally, here is another example of a collapsed lava tube, which shows off a cross-section of the top of the lava tube as well as some pahoehoe flow tops.

A collapsed lava tube on the Azorella Peninsula, Heard Island, gives a cross-sectional view of the roof of the lava tube.  Kerguelen cabbage plants in foreground are roughly 25 cm across.  Several pahoehoe flow tops are visible: small-scale in the foreground, and large-scale in the center toward the top of the image.  Image credit: Bill Mitchell (CC-BY).
A collapsed lava tube on the Azorella Peninsula, Heard Island, gives a cross-sectional view of the roof of the lava tube. Kerguelen cabbage plants in foreground are roughly 25 cm across. Several pahoehoe flow tops are visible: small-scale in the foreground, and large-scale in the center toward the top of the image. Image credit: Bill Mitchell (CC-BY).

Big Ben Gigapan

Processing the Big Ben gigapan.  Screenshot by Bill Mitchell.
Processing the Big Ben gigapan. Screenshot by Bill Mitchell.

This post is the first in a series of three on the gigapans I took on Heard Island. (Part 2, Part 3)

My first gigapan on Heard Island, this one of Big Ben, came unexpectedly. As I was out hiking one afternoon, my hiking partner, Arliss, noticed that we had a clear view of the summit of Big Ben. Clearings like this can be relatively short and infrequent, so we took a few pictures immediately. We headed back to base camp just east of Atlas Cove, arriving under an hour before sunset. The mountain was still visible, so I moved quickly to set everything up and get the gigapan taken before the light faded.

From camp, Big Ben is situated to the southeast, rising up beyond the flat sandy plain of the nullarbor. In this view, the moraines and glaciers begin about 2 km from the camera. To the right of the image is the eastern slope of Mt. Drygalski. The edge of the Azorella Peninsula lava flow is in the bottom left corner.

Glacial features dominate the landscape, including a prominent moraine now covered in vegetation (lower right). Coming toward the camera are the Schmidt and Baudissin glaciers. I think this view covers from the Allison and Vahsel glaciers (at right) to the Ealey glacier (at left).

On the Nullarbor, there are a few king penguins and elephant seals, primarily to the left of center.

Big Ben itself has a range of rock types, including basanites, alkali basalts, and trachybasalts, overlying limestones and volcanic/glacial deposits.[1-4]

[1] Quilty, P. G.; Wheller, G. (2000) Heard Island and The McDonald Islands: a Window into the Kerguelen Plateau. Papers and Proceedings of the Royal Society of Tasmania. 133 (2), 1–12.

[2] Barling, J.; Goldstein, S. L. (1990) Extreme isotopic variations in Heard Island lavas and the nature of mantle reservoirs. Nature 348:59–62, doi 10.1038/348059a0.

[3] Barling, J.; Goldstein, S. L.; Nicholls, I. A. (1994) Geochemistry of Heard Island (Southern Indian Ocean): Characterization of an Enriched Mantle Component and Implications for Enrichment of the Sub-Indian Ocean Mantle. Journal of Petrology 35:1017–1053, doi 10.1093/petrology/35.4.1017.

[4] Stephenson, J.; Barling, J.; Wheller, G.; Clarke, I. “The geology and volcanic geomorphology of Heard Island”, in Heard Island: Southern Ocean Sentinel (Eds K. Green and E. Woehler) Surrey Beatey & Sons, 2006, p. 10–27.

Back to Shore

Carlos and Bill on the prow of the Braveheart, between Heard Island and western Australia.  Image credit: Braveheart crew, used with permission.
Carlos and Bill on the prow of the Braveheart, between Heard Island and western Australia. Image credit: Braveheart crew, used with permission.

After a 10-11 day voyage, our expedition team has arrived in port. It’s good to be back on land again, though I will very much miss the company and atmosphere aboard the ship. The crew aboard the Braveheart were amazing, the food was delicious, and it was kind of fun to unplug (mostly) from the internet and civilization for a while.

Heading Home

Yellow-nosed albatross flying alongside the Braveheart.  Image credit: Bill Mitchell (CC-BY).
Yellow-nosed albatross flying alongside the Braveheart. Image credit: Bill Mitchell (CC-BY).

As may have been apparent from the silence here, we have left Heard Island and the good satellite connection we had there. Aboard the Braveheart, we have had only sparse email access on a special pared-down email account. Today, however, with good weather conditions and a very gentle sea state, we have been able to use the satellite internet terminal again.

Presently we are roughly 200 miles WSW of Fremantle, Australia, and expect to enter the harbor on Friday. The sun is beginning to set, and there is a beautiful warm light on the sea and the ship.

On board, we have been going through photographs and paring down the unusable ones, processing the good ones, exchanging images with each other, and writing descriptions of those which are of particular note or are of unusual things. Our science team have been processing samples and preparing them for shipment. Daily cloud observations and occasional 10-minute bird counts are still being performed.

Heard Island was a magnificent place to visit, and I am very glad to have had the opportunity to go. I managed to take three gigapan pictures, including one of Big Ben. I wish there had been more gigapans, but time and weather windows were quite limited and limiting. When I have a bigger, more reliable connection I’ll write more about the gigapan project results (and upload the gigapans).

There are still a few days of travel ahead, plus a flurry of activity in Fremantle. It’ll be a struggle to get photos processed and documented, enter a little data about the scientific samples, and get a couple presentations written before getting home. Even then, I will still need to write up some of the results of my scientific projects on the island.

Pictures from the Field

Standing just outside the tents at Atlas Cove, Heard Island, on a clear evening.  Note that there is no incandescence from lava on Mawson Peak.  Image credit: Adam Brown.
Standing just outside the tents at Atlas Cove, Heard Island, on a clear evening. Note that there is no incandescence from lava on Mawson Peak. Image credit: Adam Brown.

A few days have gone by, and they have been busy! We’ve been fortunate in that when the weather has been poor, the radio propagation has been good. A fair bit of windy, drizzly weather has been present this week, and we have managed to make more than 50,000 contacts with stations all around the world.

Unfortunately, the weather has meant I haven’t had the opportunity to take more gigapans. I am prepared for wet weather, and this morning I went a few hundred meters across the lake which had formed in front of camp (ankle deep) to Wharf Point, the point inside Atlas Cove. There on the cobbles lining the beach I did a stationary count of the birds in the hummocks nearby, on the water, and along the beach. It took about 10 minutes, and I managed to get the list recorded in a weatherproof notebook for upload later. Getting out of the tent and away from things for a while was a welcome change.

Inside the operating tent are many tables with radio equipment.  We have six stations set up, two of which are outside the frame to the left.  The galley is just barely showing on the right, and I'm standing in the front door.  The sleeping tent is through a little hallway.  From left to right, by leftmost extent of the head, we have Adam, Dave Lloyd, Jim, Vadym, Ken, Arliss, and Hans-Peter.  Image credit: Bill Mitchell (CC-BY)
Inside the operating tent are many tables with radio equipment. We have six stations set up, two of which are outside the frame to the left. The galley is just barely showing on the right, and I’m standing in the front door. The sleeping tent is through a little hallway. From left to right, by leftmost extent of the head, we have Adam, Dave Lloyd, Jim, Vadym, Ken, Arliss, and Hans-Peter. Image credit: Bill Mitchell (CC-BY).
The sleeping tent, which sleeps 14.  Although there are windows, they are kept shuttered all day.  It's a good place to sleep, but not particularly warm.  Image credit: Bill Mitchell (CC-BY).
The sleeping tent, which sleeps 14. Although there are windows, they are kept shuttered all day. It’s a good place to sleep, but not particularly warm. Image credit: Bill Mitchell (CC-BY).

One thing which has been abundantly clear on this expedition is that if you want to do something that depends on the weather, be prepared to do it. The weather can shift very rapidly (especially if it’s permissive weather), so “I’ll just wait until later” often won’t cut it. If you see Big Ben and want a photograph of it, get your camera and shoot. There may not be another chance. This evening I didn’t immediately take a picture when there was a clear, starry sky. I at least saw the starry sky, but did not get the photograph. With only a bit more than a week to go, I hope I can still get that picture.

In the afternoon a few days ago, the weather cleared enough to get a view of Mawson Peak atop Big Ben. I quickly grabbed the camera, put on the telephoto lens, and got a few pictures of the summit. Indeed, there was a small plume indicating (at minimum) hydrothermal activity or venting, but possibly a small active lava flow.

Mawson Peak with a small plume indicating volcanic activity.  Image credit: Bill Mitchell (CC-BY).
Mawson Peak with a small plume indicating volcanic activity. Image credit: Bill Mitchell (CC-BY).

Heard Island’s mood changes with the weather, and the effect that has on the landscape can be quite striking. The picture at the top of this post and the one immediately below are taken in pretty similar places looking in similar directions. What a difference the weather makes!

Antenna Lake, Atlas Cove, Heard Island.  Rain fell fast enough to flood much of the low-lying volcanic sand plain near our camp.  We were glad not to have camped there, and the antennas still worked.  It looks quite other-worldly, with the dark, broken lava flows and fog concealing the mountain.  Image credit: Bill Mitchell (CC-BY).
Antenna Lake, Atlas Cove, Heard Island. Rain fell fast enough to flood much of the low-lying volcanic sand plain near our camp. We were glad not to have camped there, and the antennas still worked. It looks quite other-worldly, with the dark, broken lava flows and fog concealing the mountain. Image credit: Bill Mitchell (CC-BY).
Camp seen on a rainy, dreary day typical of Heard Island.  Image credit: Bill Mitchell (CC-BY).
Camp seen on a rainy, dreary day typical of Heard Island. Image credit: Bill Mitchell (CC-BY).

Finally, the king penguins make tracks as they walk around on the wet sandy ground.

King penguin tracks in the sand of the nullarbor, Heard Island.  Each track is roughly 8 cm in length.  Image credit: Bill Mitchell (CC-BY).
King penguin tracks in the sand of the nullarbor, Heard Island. Each track is roughly 8 cm in length. Image credit: Bill Mitchell (CC-BY).